純代碼創建UI界面入門（二）

上文中是在沒有storyboard下創建UI，但是那樣的方法既繁瑣，又不符合MVC設計模式。

所以本文通過IB初始化界面，然後通過代碼動態添加UILabel和刪除UILabel

#import "ViewController.h"

@interface ViewController ()

@property (strong, nonatomic) NSMutableArray *labels;

@end

@implementation ViewController {
    NSInteger _nextY;
}

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    [self.view setBackgroundColor:[UIColor grayColor]];
    
    //初始化labels數組
    self.labels = [NSMutableArray array];
    
    //獲取主視圖的寬度
    CGRect rect = [self.view bounds];
    CGFloat width = rect.size.width;
    
    //添加按鈕設置在視圖寬度1/3處
    UIButton *addButton = [[UIButton alloc] initWithFrame:
                         CGRectMake(width/3 - 20, 50, 40, 20)];
    [addButton setTitle:@"添加" forState:UIControlStateNormal];
    [addButton addTarget:self action:@selector(add:) forControlEvents:UIControlEventTouchUpInside];
    
    [self.view addSubview:addButton];
    
    //刪除按鈕設置在視圖寬度2/3處
    UIButton *removeButton = [[UIButton alloc] initWithFrame:
                         CGRectMake(2 * width/3 - 20, 50, 40, 20)];
    [removeButton setTitle:@"刪除" forState:UIControlStateNormal];
    [removeButton addTarget:self action:@selector(remove:) forControlEvents:UIControlEventTouchUpInside];
    
    [self.view addSubview:removeButton];
    
    _nextY = 100;
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

- (IBAction)add:(id)sender {
    CGRect rect = [self.view bounds];
    CGFloat width = rect.size.width;
    //創建一個UILable控件
    UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(width/2 - 80, _nextY, 160, 30)];
    label.text = [NSString stringWithFormat:@"nextY = %ld", (long)_nextY];
    
    [self.labels addObject:label];
    [self.view addSubview:label];
    
    _nextY += 50; //控制nextY的值加50
}

- (IBAction)remove:(id)sender {
    NSLog(@"remove");
    NSLog(@"%lu",(unsigned long)[self.labels count]);
    if ([self.labels count] > 0) {
        //將最後一個labels刪除
        [[self.labels lastObject] removeFromSuperview];
        [self.labels removeLastObject];
        
        _nextY -= 50;
    }
}

@end

參考資料：《瘋狂ios講義》