修改frame快捷方法，不必再繁瑣的計算

平時計算控件frame時我們是這樣計算的：

//首先設置frame
view.frame = CGRectMake(0, 0, 320, 150);
//如果想改變其中的寬或者高或者位置，則需要重新設置frame大小，這個時候需要重新寫一遍以前設置的frame
view.frame = CGRectMake(view.frame.origin.x, 100, view.frame.size.width, view.frame.size.height);

這樣寫是不是很麻煩，如果遇到很多控件都需要改變的時候，再寫這麼多設置frame的代碼是不是很麻煩呢？那麼我們不如就直接創建一個category

一、創建一個類別：

二、寫代碼

.h 文件定義了 x, y, width, height 等方便讀寫的屬性，代碼如下：

#import <UIKit/UIKit.h>

@interface UIView (Layout)

@property (assign, nonatomic) CGFloat    top;
@property (assign, nonatomic) CGFloat    bottom;
@property (assign, nonatomic) CGFloat    left;
@property (assign, nonatomic) CGFloat    right;

@property (assign, nonatomic) CGFloat    x;
@property (assign, nonatomic) CGFloat    y;
@property (assign, nonatomic) CGPoint    origin;

@property (assign, nonatomic) CGFloat    centerX;
@property (assign, nonatomic) CGFloat    centerY;

@property (assign, nonatomic) CGFloat    width;
@property (assign, nonatomic) CGFloat    height;
@property (assign, nonatomic) CGSize    size;

@end

.m 文件實現各個屬性的setter和getter方法，代碼如下：

#import "UIView+Layout.h"

@implementation UIView (Layout)

@dynamic top;
@dynamic bottom;
@dynamic left;
@dynamic right;

@dynamic width;
@dynamic height;

@dynamic size;

@dynamic x;
@dynamic y;

- (CGFloat)top
{
    return self.frame.origin.y;
}

- (void)setTop:(CGFloat)top
{
    CGRect frame = self.frame;
    frame.origin.y = top;
    self.frame = frame;
}

- (CGFloat)left
{
    return self.frame.origin.x;
}

- (void)setLeft:(CGFloat)left
{
    CGRect frame = self.frame;
    frame.origin.x = left;
    self.frame = frame;
}

- (CGFloat)bottom
{
    return self.frame.size.height + self.frame.origin.y;
}

- (void)setBottom:(CGFloat)bottom
{
    CGRect frame = self.frame;
    frame.origin.y = bottom - frame.size.height;
    self.frame = frame;
}

- (CGFloat)right
{
    return self.frame.size.width + self.frame.origin.x;
}

- (void)setRight:(CGFloat)right
{
    CGRect frame = self.frame;
    frame.origin.x = right - frame.size.width;
    self.frame = frame;
}

- (CGFloat)x
{
    return self.frame.origin.x;
}

- (void)setX:(CGFloat)value
{
    CGRect frame = self.frame;
    frame.origin.x = value;
    self.frame = frame;
}

- (CGFloat)y
{
    return self.frame.origin.y;
}

- (void)setY:(CGFloat)value
{
    CGRect frame = self.frame;
    frame.origin.y = value;
    self.frame = frame;
}

- (CGPoint)origin
{
    return self.frame.origin;
}

- (void)setOrigin:(CGPoint)origin
{
    CGRect frame = self.frame;
    frame.origin = origin;
    self.frame = frame;
}

- (CGFloat)centerX
{
    return self.center.x;
}

- (void)setCenterX:(CGFloat)centerX
{
    CGPoint center = self.center;
    center.x = centerX;
    self.center = center;
}

- (CGFloat)centerY
{
    return self.center.y;
}

- (void)setCenterY:(CGFloat)centerY
{
    CGPoint center = self.center;
    center.y = centerY;
    self.center = center;
}

- (CGFloat)width
{
    return self.frame.size.width;
}

- (void)setWidth:(CGFloat)width
{
    CGRect frame = self.frame;
    frame.size.width = width;
    self.frame = frame;
}

- (CGFloat)height
{
    return self.frame.size.height;
}

- (void)setHeight:(CGFloat)height
{
    CGRect frame = self.frame;
    frame.size.height = height;
    self.frame = frame;
}

- (CGSize)size
{
    return self.frame.size;
}

- (void)setSize:(CGSize)size
{
    CGRect frame = self.frame;
    frame.size = size;
    self.frame = frame;
}
@end

三、使用的時候只需要導入#import "UIView+Layout.h"就可以了

view.y = 100;//改變y座標
view.x = 100;//改變x座標
view.width = 100;//改變寬度
view.height = 100;//改變高度