iOS: 学习笔记, 添加一个带界面约束的控制器
1. 创建一个空iOS应用程序(Empty Application).
2. 添加加控制器类. 修改控制器类的viewDidLoad
1 - (void)viewDidLoad 2 { 3 [super viewDidLoad]; 4 //创建标题 5 UILabel *header = [[UILabel alloc] init]; 6 header.text = @"欢迎来到我的世界!"; 7 header.textAlignment = NSTextAlignmentCenter; 8 [self.view addSubview: header]; 9 10 self.statusLabel = [[UILabel alloc] init]; 11 self.statusLabel.text = @"准备就绪!"; 12 [self.view addSubview: self.statusLabel]; 13 14 15 //添加自动布局约束 16 UILabel *statusLabel = self.statusLabel; 17 [header setTranslatesAutoresizingMaskIntoConstraints: NO]; 18 [statusLabel setTranslatesAutoresizingMaskIntoConstraints: NO]; 19 20 NSMutableArray *contraits = [NSMutableArray array]; 21 NSMutableDictionary *metrics = [[NSMutableDictionary alloc] initWithObjectsAndKeys:@5, @"HPadding", @5, @"VPadding", @20, @"TopMargin", nil]; 22 NSDictionary *views = NSDictionaryOfVariableBindings(header, statusLabel); 23 [contraits addObjectsFromArray:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-HPadding-[header]-HPadding-|" options:0 metrics:metrics views:views]]; 24 [contraits addObjectsFromArray:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-HPadding-[statusLabel]-HPadding-|" options:0 metrics:metrics views:views]]; 25 [contraits arrayByAddingObjectsFromArray:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-HPadding-[statusLabel]-HPadding-|" options:0 metrics:metrics views:views]]; 26 [contraits addObjectsFromArray:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-TopMargin-[header]-(>=0)-[statusLabel]-VPadding-|" options:0 metrics:metrics views:views]]; 27 28 [self.view addConstraints: contraits]; 29 30 }
3. 修改AppDelegate.m文件
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions { self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]]; // Override point for customization after application launch. self.window.backgroundColor = [UIColor whiteColor]; //加入控制器 self.window.rootViewController = [[DemoViewController alloc] initWithNibName:nil bundle:nil]; [self.window makeKeyAndVisible]; return YES; }
4. 运行程序, 得到如下效果
