無法應用addConstraints：NSLayoutConstraint self.window

Question

我想向狀態欄添加背景。

當我嘗試添加VFL約束self.window我得到錯誤意想不到的接口名稱： 'NSLayoutConstratint'

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions { 
    // Override point for customization after application launch. 

    UIScreen *screen=[[UIScreen alloc]init]; 

    UIWindow *window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]]; 


    self.window.makeKeyAndVisible; 

    application.statusBarStyle = UIStatusBarStyleLightContent; 

    UIView *statusBarBackgroundView = [[UIView alloc]init]; 
    statusBarBackgroundView.backgroundColor = [UIColor colorWithRed:194/255 green:31/255 blue:31/255 alpha:1]; 

    [self.window addSubview:statusBarBackgroundView]; 

// Error while adding constraint below 

    [self.window addConstraints:NSLayoutConstraint 
    constraintsWithVisualFormat:@"H:|[statusBarBackgroundView]|" 
         options:0 
         metrics:nil 
          views:NSDictionaryOfVariableBindings(statusBarBackgroundView)]; 

Answer 1

最後一行缺少方括號：

[self.window addConstraints:[NSLayoutConstraint 
constraintsWithVisualFormat:@"H:|[statusBarBackgroundView]|" 
        options:0 
        metrics:nil 
         views:NSDictionaryOfVariableBindings(statusBarBackgroundView)]];