Question

我正在练习在ViewController中呈现SecondViewController。

这就是我调用视图控制器的方式。

- (void)viewDidAppear:(BOOL)animated
{
    NSLog(@"View Did Appear" );

    SecondViewController* secViewCtrl = [ [ SecondViewController alloc ] init ];

    [ self presentViewController:secViewCtrl animated:NO completion:nil ];

}

当我运行代码时。 secondViewController继续呈现。当我从ViewDidLoad调用它时，我得到了错误的访问权限。我该如何解决这个问题。？

例如：

ViewController.m

- (void)viewDidLoad
{

    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.

}

- (void)viewDidAppear:(BOOL)animated
{
    NSLog(@"View Did Appear" );

    SecondViewController* secViewCtrl = [ [ SecondViewController alloc ] init ];

    [ self presentViewController:secViewCtrl animated:NO completion:nil ];

}

SecondViewController.m

- (void)viewDidLoad
{

    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.

    [ self.view setBackgroundColor:[ UIColor colorWithRed:64.0/255.0 green:106.0/255.0 blue:128.0/255.0 alpha:1.0 ] ];

    UIButton* backBtn = [ [ UIButton alloc ] init ];

    [ backBtn setFrame:CGRectMake(0, 0, 60, 44) ];

    [ backBtn setImage:[ UIImage imageNamed:@"Circle.png" ] forState:UIControlStateNormal ];

    [ backBtn setBackgroundColor:[ UIColor colorWithRed:0 green:0 blue:0 alpha:0.2 ] ];

    [ self.view addSubview:backBtn ];

}

我可以看到SecondViewController的颜色代码。但是当我在ViewController中记录ViewDidLoad时。它不断重复。这使我不会使用任何按钮操作。

Answer 1

看到发生了什么我会说SecondViewController是ViewController的子类。

然后当SecondViewController出现时，它会再次调用它的超类的出现方法，这将导致这个无限循环。

如果是这种情况，只需将SecondViewController设置为UIViewController子类，而不是ViewController

Answer 2

尝试将此代码放在方法中并从viewDidAppear调用该方法：with performSelectorOnMainThread：

在呈现SecondViewController时，ViewDidAppear会重复调用

2 个答案: