无法在第一个视图控制器顶部嵌入第二个视图控制器

Question

使用下面的代码在第二个视图控制器顶部显示第一个视图控制器就像对话框一样。

[self addChildViewController:viewController]; 
viewController.view.frame = self.view.frame; 
[self.view addSubview:viewController.view]; 
viewController.view.alpha = 0; 
[viewController didMoveToParentViewController:self]; 

[UIView animateWithDuration:0.25 delay:0.0 options:UIViewAnimationOptionCurveLinear animations:^ 
{ 
    viewController.view.alpha = 1; 
} 
       completion:nil]; 

但第二个视图控制器是不可见的...我如何能排序了这一点？

Answer 1

必须有，你犯的错误代码，我写了一个演示： 我写两个控制器这样的：

在vc1：

#import "ViewController.h" 
#import "ViewController2.h" 

@interface ViewController() 

@end 

@implementation ViewController 

- (void)viewDidLoad { 
    [super viewDidLoad]; 

    [self initUI]; 
} 

#pragma mark - init 

- (void)initUI { 

self.view.backgroundColor = [UIColor whiteColor]; 

A) If use storyboard, init vc2 like this : 
UIStoryboard *sb = [UIStoryboard storyboardWithName:@"Main" bundle:nil]; 
ViewController2 *vc2 = [sb instantiateViewControllerWithIdentifier:@"ViewController2"]; 

B)If use code ,init vc2 like this: 
ViewController2 *vc2 = [[ViewController2 alloc] init]; 


[self addChildViewController:vc2]; 
vc2.view.frame = self.view.bounds 
[self.view addSubview:vc2.view]; 
vc2.view.alpha = 0; 
[vc2 didMoveToParentViewController:self]; 

[UIView animateWithDuration:0.25 delay:0.0 options:UIViewAnimationOptionCurveLinear animations:^ 
    { 
     vc2.view.alpha = 1; 
    } 
       completion:nil]; 
} 

@end 

在vc2：

#import "ViewController2.h" 

@interface ViewController2() 

@end 

@implementation ViewController2 

- (void)viewDidLoad { 
    [super viewDidLoad]; 
    // Do any additional setup after loading the view. 

    self.view.backgroundColor = [UIColor brownColor]; 

} 

Answer 2

1. 尝试[parentView bringSubviewToFront:childView];

2. 尝试viewController.view.frame = self.view.bounds;

3. 做检查，如果你有实例viewController正常。