如何使用Swift以編程方式添加約束

原創 xfxf996 2020-05-18 15:20

本文翻譯自：How to add constraints programmatically using Swift

I'm trying to figure this out since last week without going any step further. 自上週以來，我一直在試圖解決這個問題，而無需採取任何進一步措施。 Ok, so I need to apply some constraints programmatically in Swift to a UIView using this code: 好的，因此我需要使用以下代碼在Swift中以編程方式將某些約束應用於UIView ： 

var new_view:UIView! = UIView(frame: CGRectMake(0, 0, 100, 100));
new_view.backgroundColor = UIColor.redColor();
view.addSubview(new_view);

var constX:NSLayoutConstraint = NSLayoutConstraint(item: new_view, attribute: NSLayoutAttribute.CenterX, relatedBy: NSLayoutRelation.Equal, toItem: self.view, attribute: NSLayoutAttribute.CenterX, multiplier: 1, constant: 0);
self.view.addConstraint(constX);

var constY:NSLayoutConstraint = NSLayoutConstraint(item: new_view, attribute: NSLayoutAttribute.CenterY, relatedBy: NSLayoutRelation.Equal, toItem: self.view, attribute: NSLayoutAttribute.CenterY, multiplier: 1, constant: 0);
self.view.addConstraint(constY);

var constW:NSLayoutConstraint = NSLayoutConstraint(item: new_view, attribute: NSLayoutAttribute.Width, relatedBy: NSLayoutRelation.Equal, toItem: new_view, attribute: NSLayoutAttribute.Width, multiplier: 1, constant: 0);
self.view.addConstraint(constW);

var constH:NSLayoutConstraint = NSLayoutConstraint(item: new_view, attribute: NSLayoutAttribute.Height, relatedBy: NSLayoutRelation.Equal, toItem: new_view, attribute: NSLayoutAttribute.Height, multiplier: 1, constant: 0);
self.view.addConstraint(constH);

But Xcode returns this weird output: 但是Xcode返回這個奇怪的輸出： 

2014-10-03 09:48:12.657 Test[35088:2454916] Unable to simultaneously satisfy constraints.  Probably at least one of the constraints in the following list is one you don't want. Try this: (1) look at each constraint and try to figure out which you don't expect; (2) find the code that added the unwanted constraint or constraints and fix it. (Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't understand, refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints) 
(
"<NSLayoutConstraint:0x7fa4ea446830 UIView:0x7fa4ea429290.centerX == UIView:0x7fa4ea4470f0.centerX>",
"<NSAutoresizingMaskLayoutConstraint:0x7fa4ea4516c0 h=--& v=--& UIView:0x7fa4ea429290.midX == + 50>",
"<NSLayoutConstraint:0x7fa4ea452830 'UIView-Encapsulated-Layout-Width' H:[UIView:0x7fa4ea4470f0(375)]>",
"<NSAutoresizingMaskLayoutConstraint:0x7fa4ea446db0 h=-&- v=-&- 'UIView-Encapsulated-Layout-Left' H:|-(0)-[UIView:0x7fa4ea4470f0]   (Names: '|':UIWindow:0x7fa4ea444b20 )>"
)

Will attempt to recover by breaking constraint <NSLayoutConstraint:0x7fa4ea446830 UIView:0x7fa4ea429290.centerX == UIView:0x7fa4ea4470f0.centerX>

Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger. The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in
<UIKit/UIView.h> may also be helpful.

2014-10-03 09:48:12.658 Test[35088:2454916] Unable to simultaneously satisfy constraints.  Probably at least one of the constraints in the following list is one you don't want. Try this: (1) look at each constraint and try to figure out which you don't expect; (2) find the code that added the unwanted constraint or constraints and fix it. (Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't understand, refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints)
(
"<NSLayoutConstraint:0x7fa4ea44d160 UIView:0x7fa4ea429290.centerY == UIView:0x7fa4ea4470f0.centerY>",
"<NSAutoresizingMaskLayoutConstraint:0x7fa4ea451b30 h=--& v=--& UIView:0x7fa4ea429290.midY == + 50>",
"<NSLayoutConstraint:0x7fa4ea44cf00 'UIView-Encapsulated-Layout-Height' V:[UIView:0x7fa4ea4470f0(667)]>",
"<NSAutoresizingMaskLayoutConstraint:0x7fa4ea452700 h=-&- v=-&- 'UIView-Encapsulated-Layout-Top' V:|-(0)-[UIView:0x7fa4ea4470f0]  (Names: '|':UIWindow:0x7fa4ea444b20 )>"
)

Will attempt to recover by breaking constraint <NSLayoutConstraint:0x7fa4ea44d160 UIView:0x7fa4ea429290.centerY == UIView:0x7fa4ea4470f0.centerY>

Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger. The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKit/UIView.h> may also be helpful.

Can you help me? 你能幫助我嗎？ Thanks a lot 非常感謝

#1樓

參考：https://stackoom.com/question/1lqpK/如何使用Swift以編程方式添加約束

#2樓

Do you plan to have a squared UIView of width: 100 and Height: 100 centered inside the UIView of an UIViewController ? 您是否打算在UIViewController的UIView中居中放置一個寬度爲100和高度爲100的平方UIView ？ If so, you may try one of the 6 following Auto Layout styles (Swift 5 / iOS 12.2): 如果是這樣，您可以嘗試以下6種自動佈局樣式之一（Swift 5 / iOS 12.2）：

1. Using NSLayoutConstraint initializer 1.使用NSLayoutConstraint初始化程序 

override func viewDidLoad() {
    let newView = UIView()
    newView.backgroundColor = UIColor.red
    view.addSubview(newView)

    newView.translatesAutoresizingMaskIntoConstraints = false
    let horizontalConstraint = NSLayoutConstraint(item: newView, attribute: NSLayoutConstraint.Attribute.centerX, relatedBy: NSLayoutConstraint.Relation.equal, toItem: view, attribute: NSLayoutConstraint.Attribute.centerX, multiplier: 1, constant: 0)
    let verticalConstraint = NSLayoutConstraint(item: newView, attribute: NSLayoutConstraint.Attribute.centerY, relatedBy: NSLayoutConstraint.Relation.equal, toItem: view, attribute: NSLayoutConstraint.Attribute.centerY, multiplier: 1, constant: 0)
    let widthConstraint = NSLayoutConstraint(item: newView, attribute: NSLayoutConstraint.Attribute.width, relatedBy: NSLayoutConstraint.Relation.equal, toItem: nil, attribute: NSLayoutConstraint.Attribute.notAnAttribute, multiplier: 1, constant: 100)
    let heightConstraint = NSLayoutConstraint(item: newView, attribute: NSLayoutConstraint.Attribute.height, relatedBy: NSLayoutConstraint.Relation.equal, toItem: nil, attribute: NSLayoutConstraint.Attribute.notAnAttribute, multiplier: 1, constant: 100)
    view.addConstraints([horizontalConstraint, verticalConstraint, widthConstraint, heightConstraint])
}

override func viewDidLoad() {
    let newView = UIView()
    newView.backgroundColor = UIColor.red
    view.addSubview(newView)

    newView.translatesAutoresizingMaskIntoConstraints = false
    let horizontalConstraint = NSLayoutConstraint(item: newView, attribute: NSLayoutConstraint.Attribute.centerX, relatedBy: NSLayoutConstraint.Relation.equal, toItem: view, attribute: NSLayoutConstraint.Attribute.centerX, multiplier: 1, constant: 0)
    let verticalConstraint = NSLayoutConstraint(item: newView, attribute: NSLayoutConstraint.Attribute.centerY, relatedBy: NSLayoutConstraint.Relation.equal, toItem: view, attribute: NSLayoutConstraint.Attribute.centerY, multiplier: 1, constant: 0)
    let widthConstraint = NSLayoutConstraint(item: newView, attribute: NSLayoutConstraint.Attribute.width, relatedBy: NSLayoutConstraint.Relation.equal, toItem: nil, attribute: NSLayoutConstraint.Attribute.notAnAttribute, multiplier: 1, constant: 100)
    let heightConstraint = NSLayoutConstraint(item: newView, attribute: NSLayoutConstraint.Attribute.height, relatedBy: NSLayoutConstraint.Relation.equal, toItem: nil, attribute: NSLayoutConstraint.Attribute.notAnAttribute, multiplier: 1, constant: 100)
    NSLayoutConstraint.activate([horizontalConstraint, verticalConstraint, widthConstraint, heightConstraint])
}

override func viewDidLoad() {
    let newView = UIView()
    newView.backgroundColor = UIColor.red
    view.addSubview(newView)

    newView.translatesAutoresizingMaskIntoConstraints = false
    NSLayoutConstraint(item: newView, attribute: NSLayoutConstraint.Attribute.centerX, relatedBy: NSLayoutConstraint.Relation.equal, toItem: view, attribute: NSLayoutConstraint.Attribute.centerX, multiplier: 1, constant: 0).isActive = true
    NSLayoutConstraint(item: newView, attribute: NSLayoutConstraint.Attribute.centerY, relatedBy: NSLayoutConstraint.Relation.equal, toItem: view, attribute: NSLayoutConstraint.Attribute.centerY, multiplier: 1, constant: 0).isActive = true
    NSLayoutConstraint(item: newView, attribute: NSLayoutConstraint.Attribute.width, relatedBy: NSLayoutConstraint.Relation.equal, toItem: nil, attribute: NSLayoutConstraint.Attribute.notAnAttribute, multiplier: 1, constant: 100).isActive = true
    NSLayoutConstraint(item: newView, attribute: NSLayoutConstraint.Attribute.height, relatedBy: NSLayoutConstraint.Relation.equal, toItem: nil, attribute: NSLayoutConstraint.Attribute.notAnAttribute, multiplier: 1, constant: 100).isActive = true
}

2. Using Visual Format Language 2.使用視覺格式語言 

override func viewDidLoad() {
    let newView = UIView()
    newView.backgroundColor = UIColor.red
    view.addSubview(newView)

    newView.translatesAutoresizingMaskIntoConstraints = false
    let views = ["view": view!, "newView": newView]
    let horizontalConstraints = NSLayoutConstraint.constraints(withVisualFormat: "H:[view]-(<=0)-[newView(100)]", options: NSLayoutConstraint.FormatOptions.alignAllCenterY, metrics: nil, views: views)
    let verticalConstraints = NSLayoutConstraint.constraints(withVisualFormat: "V:[view]-(<=0)-[newView(100)]", options: NSLayoutConstraint.FormatOptions.alignAllCenterX, metrics: nil, views: views)
    view.addConstraints(horizontalConstraints)
    view.addConstraints(verticalConstraints)
}

override func viewDidLoad() {
    let newView = UIView()
    newView.backgroundColor = UIColor.red
    view.addSubview(newView)

    newView.translatesAutoresizingMaskIntoConstraints = false
    let views = ["view": view!, "newView": newView]
    let horizontalConstraints = NSLayoutConstraint.constraints(withVisualFormat: "H:[view]-(<=0)-[newView(100)]", options: NSLayoutConstraint.FormatOptions.alignAllCenterY, metrics: nil, views: views)
    let verticalConstraints = NSLayoutConstraint.constraints(withVisualFormat: "V:[view]-(<=0)-[newView(100)]", options: NSLayoutConstraint.FormatOptions.alignAllCenterX, metrics: nil, views: views)
    NSLayoutConstraint.activate(horizontalConstraints)
    NSLayoutConstraint.activate(verticalConstraints)
}

3. Using a mix of NSLayoutConstraint initializer and Visual Format Language 3.結合使用NSLayoutConstraint初始化程序和Visual Format Language 

override func viewDidLoad() {
    let newView = UIView()
    newView.backgroundColor = UIColor.red
    view.addSubview(newView)

    newView.translatesAutoresizingMaskIntoConstraints = false
    let views = ["newView": newView]
    let widthConstraints = NSLayoutConstraint.constraints(withVisualFormat: "H:[newView(100)]", options: NSLayoutConstraint.FormatOptions(rawValue: 0), metrics: nil, views: views)
    let heightConstraints = NSLayoutConstraint.constraints(withVisualFormat: "V:[newView(100)]", options: NSLayoutConstraint.FormatOptions(rawValue: 0), metrics: nil, views: views)
    let horizontalConstraint = NSLayoutConstraint(item: newView, attribute: NSLayoutConstraint.Attribute.centerX, relatedBy: NSLayoutConstraint.Relation.equal, toItem: view, attribute: NSLayoutConstraint.Attribute.centerX, multiplier: 1, constant: 0)
    let verticalConstraint = NSLayoutConstraint(item: newView, attribute: NSLayoutConstraint.Attribute.centerY, relatedBy: NSLayoutConstraint.Relation.equal, toItem: view, attribute: NSLayoutConstraint.Attribute.centerY, multiplier: 1, constant: 0)
    view.addConstraints(widthConstraints)
    view.addConstraints(heightConstraints)
    view.addConstraints([horizontalConstraint, verticalConstraint])
}

override func viewDidLoad() {
    let newView = UIView()
    newView.backgroundColor = UIColor.red
    view.addSubview(newView)

    newView.translatesAutoresizingMaskIntoConstraints = false
    let views = ["newView": newView]
    let widthConstraints = NSLayoutConstraint.constraints(withVisualFormat: "H:[newView(100)]", options: NSLayoutConstraint.FormatOptions(rawValue: 0), metrics: nil, views: views)
    let heightConstraints = NSLayoutConstraint.constraints(withVisualFormat: "V:[newView(100)]", options: NSLayoutConstraint.FormatOptions(rawValue: 0), metrics: nil, views: views)
    let horizontalConstraint = NSLayoutConstraint(item: newView, attribute: NSLayoutConstraint.Attribute.centerX, relatedBy: NSLayoutConstraint.Relation.equal, toItem: view, attribute: NSLayoutConstraint.Attribute.centerX, multiplier: 1, constant: 0)
    let verticalConstraint = NSLayoutConstraint(item: newView, attribute: NSLayoutConstraint.Attribute.centerY, relatedBy: NSLayoutConstraint.Relation.equal, toItem: view, attribute: NSLayoutConstraint.Attribute.centerY, multiplier: 1, constant: 0)
    NSLayoutConstraint.activate(widthConstraints)
    NSLayoutConstraint.activate(heightConstraints)
    NSLayoutConstraint.activate([horizontalConstraint, verticalConstraint])
}

override func viewDidLoad() {
    let newView = UIView()
    newView.backgroundColor = UIColor.red
    view.addSubview(newView)

    newView.translatesAutoresizingMaskIntoConstraints = false
    let views = ["newView": newView]
    let widthConstraints = NSLayoutConstraint.constraints(withVisualFormat: "H:[newView(100)]", options: NSLayoutConstraint.FormatOptions(rawValue: 0), metrics: nil, views: views)
    let heightConstraints = NSLayoutConstraint.constraints(withVisualFormat: "V:[newView(100)]", options: NSLayoutConstraint.FormatOptions(rawValue: 0), metrics: nil, views: views)
    NSLayoutConstraint.activate(widthConstraints)
    NSLayoutConstraint.activate(heightConstraints)
    NSLayoutConstraint(item: newView, attribute: NSLayoutConstraint.Attribute.centerX, relatedBy: NSLayoutConstraint.Relation.equal, toItem: view, attribute: NSLayoutConstraint.Attribute.centerX, multiplier: 1, constant: 0).isActive = true
    NSLayoutConstraint(item: newView, attribute: NSLayoutConstraint.Attribute.centerY, relatedBy: NSLayoutConstraint.Relation.equal, toItem: view, attribute: NSLayoutConstraint.Attribute.centerY, multiplier: 1, constant: 0).isActive = true
}

4. Using UIView.AutoresizingMask 4.使用UIView.AutoresizingMask

Note: Springs and Struts will be translated into corresponding auto layout constraints at runtime. 注意：Springs和Struts將在運行時轉換爲相應的自動佈局約束。 

override func viewDidLoad() {
    let newView = UIView(frame: CGRect(x: 0, y: 0, width: 100, height: 100))
    newView.backgroundColor = UIColor.red
    view.addSubview(newView)

    newView.translatesAutoresizingMaskIntoConstraints = true
    newView.center = CGPoint(x: view.bounds.midX, y: view.bounds.midY)
    newView.autoresizingMask = [UIView.AutoresizingMask.flexibleLeftMargin, UIView.AutoresizingMask.flexibleRightMargin, UIView.AutoresizingMask.flexibleTopMargin, UIView.AutoresizingMask.flexibleBottomMargin]
}

5. Using NSLayoutAnchor 5.使用NSLayoutAnchor 

override func viewDidLoad() {
    let newView = UIView()
    newView.backgroundColor = UIColor.red
    view.addSubview(newView)

    newView.translatesAutoresizingMaskIntoConstraints = false
    let horizontalConstraint = newView.centerXAnchor.constraint(equalTo: view.centerXAnchor)
    let verticalConstraint = newView.centerYAnchor.constraint(equalTo: view.centerYAnchor)
    let widthConstraint = newView.widthAnchor.constraint(equalToConstant: 100)
    let heightConstraint = newView.heightAnchor.constraint(equalToConstant: 100)
    view.addConstraints([horizontalConstraint, verticalConstraint, widthConstraint, heightConstraint])
}

override func viewDidLoad() {
    let newView = UIView()
    newView.backgroundColor = UIColor.red
    view.addSubview(newView)

    newView.translatesAutoresizingMaskIntoConstraints = false
    let horizontalConstraint = newView.centerXAnchor.constraint(equalTo: view.centerXAnchor)
    let verticalConstraint = newView.centerYAnchor.constraint(equalTo: view.centerYAnchor)
    let widthConstraint = newView.widthAnchor.constraint(equalToConstant: 100)
    let heightConstraint = newView.heightAnchor.constraint(equalToConstant: 100)
    NSLayoutConstraint.activate([horizontalConstraint, verticalConstraint, widthConstraint, heightConstraint])
}

override func viewDidLoad() {
    let newView = UIView()
    newView.backgroundColor = UIColor.red
    view.addSubview(newView)

    newView.translatesAutoresizingMaskIntoConstraints = false
    newView.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
    newView.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true
    newView.widthAnchor.constraint(equalToConstant: 100).isActive = true
    newView.heightAnchor.constraint(equalToConstant: 100).isActive = true
}

6. Using intrinsicContentSize and NSLayoutAnchor 6.使用intrinsicContentSize和NSLayoutAnchor 

import UIKit

class CustomView: UIView {

    override var intrinsicContentSize: CGSize {
        return CGSize(width: 100, height: 100)
    }

}

class ViewController: UIViewController {

    override func viewDidLoad() {
        let newView = CustomView()
        newView.backgroundColor = UIColor.red
        view.addSubview(newView)

        newView.translatesAutoresizingMaskIntoConstraints = false
        let horizontalConstraint = newView.centerXAnchor.constraint(equalTo: view.centerXAnchor)
        let verticalConstraint = newView.centerYAnchor.constraint(equalTo: view.centerYAnchor)
        NSLayoutConstraint.activate([horizontalConstraint, verticalConstraint])
    }

}

Result: 結果：

在此處輸入圖片說明

#3樓

The problem, as the error message suggests, is that you have constraints of type NSAutoresizingMaskLayoutConstraints that conflict with your explicit constraints, because new_view.translatesAutoresizingMaskIntoConstraints is set to true. 如錯誤消息所暗示的那樣，問題在於您具有與明確約束衝突的NSAutoresizingMaskLayoutConstraints類型約束，因爲new_view.translatesAutoresizingMaskIntoConstraints設置爲true。

This is the default setting for views you create in code. 這是您在代碼中創建的視圖的默認設置。 You can turn it off like this: 您可以這樣關閉它： 

var new_view:UIView! = UIView(frame: CGRectMake(0, 0, 100, 100))
new_view.translatesAutoresizingMaskIntoConstraints = false

Also, your width and height constraints are weird. 另外，您的寬度和高度限制很奇怪。 If you want the view to have a constant width, this is the proper way: 如果希望視圖具有恆定的寬度，這是正確的方法： 

new_view.addConstraint(NSLayoutConstraint(
    item:new_view, attribute:NSLayoutAttribute.Width,
    relatedBy:NSLayoutRelation.Equal,
    toItem:nil, attribute:NSLayoutAttribute.NotAnAttribute,
    multiplier:0, constant:100))

(Replace 100 by the width you want it to have.) （將100替換爲所需的寬度。）

If your deployment target is iOS 9.0 or later, you can use this shorter code: 如果您的部署目標是iOS 9.0或更高版本，則可以使用以下較短的代碼： 

new_view.widthAnchor.constraintEqualToConstant(100).active = true

Anyway, for a layout like this (fixed size and centered in parent view), it would be simpler to use the autoresizing mask and let the system translate the mask into constraints: 無論如何，對於這樣的佈局（固定大小並在父視圖中居中），使用自動調整大小蒙版並使系統將蒙版轉換爲約束會更簡單： 

var new_view:UIView! = UIView(frame: CGRectMake(0, 0, 100, 100))
new_view.backgroundColor = UIColor.redColor();
view.addSubview(new_view);

// This is the default setting but be explicit anyway...
new_view.translatesAutoresizingMaskIntoConstraints = true

new_view.autoresizingMask = [ .FlexibleTopMargin, .FlexibleBottomMargin,
    .FlexibleLeftMargin, .FlexibleRightMargin ]

new_view.center = CGPointMake(view.bounds.midX, view.bounds.midY)

Note that using autoresizing is perfectly legitimate even when you're also using autolayout. 請注意，即使同時使用自動版式，使用自動調整大小也是完全合理的。 (UIKit still uses autoresizing in lots of places internally.) The problem is that it's difficult to apply additional constraints to a view that is using autoresizing. （UIKit在內部仍在許多地方使用自動調整大小。）問題是，難以對正在使用自動調整大小的視圖應用其他約束。

#4樓

    var xCenterConstraint : NSLayoutConstraint!
    var yCenterConstraint: NSLayoutConstraint!

 xCenterConstraint = NSLayoutConstraint(item: self.view, attribute: .CenterX, relatedBy: .Equal, toItem: (Your view NAme), attribute: .CenterX, multiplier: 1, constant: 0)
            self.view.addConstraint(xCenterConstraint)

 yCenterConstraint = NSLayoutConstraint(item: self.view, attribute: .CenterY, relatedBy: .Equal, toItem: (Your view Name), attribute: .CenterY, multiplier: 1, constant: 0)
            self.view.addConstraint(yCenterConstraint)

#5樓

It helps me to learn visually, so this is a supplemental answer. 它可以幫助我進行視覺學習，所以這是一個補充性答案。

Boilerplate code 樣板代碼 

override func viewDidLoad() {
    super.viewDidLoad()

    let myView = UIView()
    myView.backgroundColor = UIColor.blue
    myView.translatesAutoresizingMaskIntoConstraints = false
    view.addSubview(myView)

    // Add constraints code here
    // ...
}

Each of the following examples are independent of the others. 以下每個示例均獨立於其他示例。

Pin left edge 針左邊緣

myView.leading = leadingMargin + 20

在此處輸入圖片說明

Method 1: Anchor Style 方法1：錨樣式 

let margins = view.layoutMarginsGuide
myView.leadingAnchor.constraint(equalTo: margins.leadingAnchor, constant: 20).isActive = true
  • In addition to leadingAnchor , there is also trailingAnchor , topAnchor , and bottomAnchor . 除了leadingAnchor ，也有trailingAnchor ， topAnchor和bottomAnchor 。

Method 2: NSLayoutConstraint Style 方法2：NSLayoutConstraint樣式 

NSLayoutConstraint(item: myView, attribute: NSLayoutAttribute.leading, relatedBy: NSLayoutRelation.equal, toItem: view, attribute: NSLayoutAttribute.leadingMargin, multiplier: 1.0, constant: 20.0).isActive = true
  • In addition to .leading there is also .trailing , .top , and .bottom . 除了.leading這裏還.trailing ， .top和.bottom 。
  • In addition to .leadingMargin there is also .trailingMargin , .topMargin , and .bottomMargin . 除了.leadingMargin之外，還有.trailingMargin ， .topMargin和.bottomMargin 。

Set Width and Height 設置寬度和高度

width = 200
height = 100

在此處輸入圖片說明

Method 1: Anchor Style 方法1：錨樣式 

myView.widthAnchor.constraint(equalToConstant: 200).isActive = true
myView.heightAnchor.constraint(equalToConstant: 100).isActive = true

Method 2: NSLayoutConstraint Style 方法2：NSLayoutConstraint樣式 

NSLayoutConstraint(item: myView, attribute: NSLayoutAttribute.width, relatedBy: NSLayoutRelation.equal, toItem: nil, attribute: NSLayoutAttribute.notAnAttribute, multiplier: 1, constant: 200).isActive = true
NSLayoutConstraint(item: myView, attribute: NSLayoutAttribute.height, relatedBy: NSLayoutRelation.equal, toItem: nil, attribute: NSLayoutAttribute.notAnAttribute, multiplier: 1, constant: 100).isActive = true

Center in container 容器中心

myView.centerX = centerX
myView.centerY = centerY

在此處輸入圖片說明

Method 1: Anchor Style 方法1：錨樣式 

myView.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
myView.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true

Method 2: NSLayoutConstraint Style 方法2：NSLayoutConstraint樣式 

NSLayoutConstraint(item: myView, attribute: NSLayoutAttribute.centerX, relatedBy: NSLayoutRelation.equal, toItem: view, attribute: NSLayoutAttribute.centerX, multiplier: 1, constant: 0).isActive = true
NSLayoutConstraint(item: myView, attribute: NSLayoutAttribute.centerY, relatedBy: NSLayoutRelation.equal, toItem: view, attribute: NSLayoutAttribute.centerY, multiplier: 1, constant: 0).isActive = true

Notes 筆記

  • Anchor style is the preferred method over NSLayoutConstraint Style, however it is only available from iOS 9, so if you are supporting iOS 8 then you should still use NSLayoutConstraint Style. 錨樣式是NSLayoutConstraint樣式的首選方法，但是僅iOS 9提供了NSLayoutConstraint樣式，因此，如果支持iOS 8，則仍應使用NSLayoutConstraint樣式。
  • The examples above showed just the one or two constraints that were being focused on. 上面的示例僅顯示了要關注的一兩個約束。 However, in order to properly place myView in my test project I needed to have four constraints. 但是，爲了將myView正確放置在測試項目中，我需要具有四個約束。

Further Reading 進一步閱讀

#6樓

You are adding all defined constraints to self.view which is wrong, as width and height constraint should be added to your newView . 您正在將所有定義的約束self.view這是不對的，因爲寬度和高度的限制應添加到您的newView 。

Also, as I understand you want to set constant width and height 100:100. 另外，據我瞭解，您想將寬度和高度設置爲恆定的100：100。 In this case you should change your code to: 在這種情況下，您應該將代碼更改爲： 

var constW = NSLayoutConstraint(item: newView, 
    attribute: .Width, 
    relatedBy: .Equal, 
    toItem: nil, 
    attribute: .NotAnAttribute, 
    multiplier: 1, 
    constant: 100)
newView.addConstraint(constW)

var constH = NSLayoutConstraint(item: newView, 
    attribute: .Height, 
    relatedBy: .Equal, 
    toItem: nil, 
    attribute: .NotAnAttribute, 
    multiplier: 1, 
    constant: 100)
newView.addConstraint(constH)
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0x01 獲取webshell 在各種信息蒐集中，發現某個ip的端口掛着一個比較老的服務。 首先看到了員工工號和手機號的雙重驗證，也不知道賬號是什麼結構組成的，基本上放棄字典爆破這一條路。於是乎打開之前用燈塔的掃描結果，看看文件泄露是否

原創 2024-05-17 23:16:30

記一次特別的未授權訪問

某個夜裏，隨手點進去的一個小程序，引發的連鎖反應。 開局一個小程序： 登錄方式令人發愁，嘗試收集，無果。 數據交互的地方說不定有sql，再次嘗試，還是無果。 複製連接去web端，看看有沒有什麼收穫： 好熟悉的界面，這不是SpringB

原創 2024-05-13 23:18:59

O2OA平臺手機移動端APP功能簡介

O2OA平臺擁有配套的原生開發的安卓和IOS移動APP，開發者在擁有公網IP或者域名的服務器上可以輕鬆體驗移動辦公環境。本篇主要向大家簡要介紹移動APP的主機功能。   O2OA 有自研的移動端 APP ，使用這個 APP 可

原創 2024-05-09 23:10:13

CVE復現之老洞新探（CVE-2021-3156）

環境搭建 直接拉取合適的docker docker 環境： https://hub.docker.com/r/chenaotian/cve-2021-3156 下載glibc-2.27源碼和sudo-1.8.21源碼 漏洞分析

原創 2024-05-08 22:52:37

跨平臺美學！使用DevExpress Reports & Office File API時如何管理字體？

DevExpress Office File API是一個專爲C#, VB.NET 和 ASP.NET等開發人員提供的非可視化.NET庫。有了這個庫，不用安裝Microsoft Office，就可以完全自動處理Excel、Word等文檔。開

原創 2024-05-06 23:35:34

記一次北京某大學邏輯漏洞挖掘

0x01 信息收集 個人覺得教育src的漏洞挖掘就不需要找真實IP了，我們直接進入正題，收集某大學的子域名，可以用oneforall，這裏給大家推薦一個在線查詢子域名的網站：https://www.virustotal.com/ 收集到的子

原創 2024-04-28 22:47:25

一次奇妙的任意用戶登錄實戰

剛剛進行了微信sessionkey的學習，正準備實戰一下，就發現了這個神奇的網站，預知後事如何。請繼續向下看去 1. 目標 2. 開局一個登錄框 3. 首先，直接弱口令走起來，萬一留有測試的賬號呢 嘗試，1311111111，1333

原創 2024-04-22 22:46:11

記一次奇妙的某個edu滲透測試

前話： 對登錄方法的輕視造成一系列的漏洞出現，對接口確實鑑權造成大量的信息泄露。從小程序到web端網址的奇妙的測試就此開始。（文章厚碼，請見諒） 1. 尋找到目標站點的小程序 進入登錄發現只需要姓名加學工號就能成功登錄，通過google

原創 2024-04-16 22:46:34

記一次對某高校微信小程序的漏洞挖掘

挖掘目標的部署在微信的資產(減少信息的收集，畢竟一般web站點沒有賬號密碼不好進入後臺，挖掘功能點少) 1.尋找目標的微信小程序(非原圖) 2.招生小程序打不開，只能挖掘管理系統 進入後發現存在上報安全隱患功能，可以上傳圖片 3.準備上

原創 2024-04-15 22:48:12

Objective-C網絡請求開發的高效實現方法與技巧

前言 在移動應用開發中，網絡請求是一項至關重要的技術。Objective-C作爲iOS平臺的主要開發語言之一，擁有豐富的網絡請求開發工具和技術。本文將介紹如何利用Objective-C語言實現高效的網絡請求，以及一些實用的技巧和方法。

原創 2024-04-12 23:25:47

從CVE復現看棧溢出漏洞利用

最近復現了兩個棧溢出漏洞的cve，分別是CVE-2017-9430和CVE-2017-13089，簡單記錄一下real wrold中的棧溢出漏洞學習。目前，棧溢出漏洞主要出現在iot固件中，linux下的已經很少了，所以這兩個洞都是17年，

原創 2024-04-12 10:45:32

“AI換臉”色情視頻困擾英國，6成女性擔心成受害者

AI換臉，也稱爲“深度僞造”（Deepfake），是一種利用人工智能技術將人臉替換到另一個人的臉部上的技術。“深度僞造”技術涉及多種技術和算法，可以生成非常逼真的圖像或視頻。將“深度僞造”的虛假內容與真實信息的元素拼湊在一起，就可以用於可以

原創 2024-04-09 23:33:10

關於轉義符 \ 在php正則中的匹配問題

今天做題遇到一個很經典的問題，記錄一下，先看一段代碼 <?php $str，=，"\\"; $pattern，=，"/\\/"; if(preg_match($partern,$str,$arr)) { ，，，，echo，"suc

原創 2024-04-09 22:46:30

Vision Pro開發實踐（一）

簡介 Vision Pro是蘋果公司的首款頭戴式“空間計算”顯示設備，於2023年6月6日在“WWDC2023”正式發佈，同時推出的還有專爲Vision Pro打造的操作系統平臺visionOS，以及一整套“新的”開發工具，之所以打引號，

原創 2024-04-07 11:15:26

聊聊Swift中的宏

聊聊Swift中的宏 宏，Macros是一種常見的編程技術，傳統的C語言中，即包含了宏功能。宏這種功能，簡單來說是在代碼的預編譯階段進行靜態替換，是一種非運行時的特性。但是往復雜了說，宏實際上也提供了一種”元編程“方式，即對程序本身進行編程

原創 2024-04-18 23:26:09