如何在父视图上添加子视图控制器的视图

Question

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

    ChildViewController *childviewcontroller = [[ChildViewController alloc] initWithNibName:@"ChildViewController" bundle:nil];


    [self addChildViewController:childviewcontroller];
    [self.view addSubview:childviewcontroller.view];
    [childviewcontroller willMoveToParentViewController:self];
    UIView *cview = [[UIView alloc] init];
    cview = childviewcontroller.view;
    [self.view removeConstraints:self.view.constraints];

    NSDictionary *viewsDictionary = NSDictionaryOfVariableBindings(cview);
    [self.view addConstraints:[NSLayoutConstraint 
                                constraintsWithVisualFormat:@"H:|-[cview]-|" 
                                                    options:0 metrics:nil                                        
                                                    views:viewsDictionary]];

}

我想在父视图上添加childviewcontroller视图。 添加后我设置了约束，但它对我不起作用。

我也收到这样的警告

2013-07-25 10:47:30.564 neenah[1105:c07] Unable to simultaneously satisfy constraints.
    Probably at least one of the constraints in the following list is one you don't want. 
    Try this: (1) look at each constraint and try to figure out which you don't expect; 
    (2) find the code that added the unwanted constraint or constraints and fix it. 
    (Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't 
    understand, refer to the documentation for the UIView 
    property translatesAutoresizingMaskIntoConstraints) 
(
    "<NSLayoutConstraint:0x9256c90 H:|-(NSSpace(20))-[UIView:0x9256a00]   (Names: '|':UIView:0x92557a0 )>",
    "<NSAutoresizingMaskLayoutConstraint:0x755d690 h=--& v=--& H:[UIView:0x9256a00(320)]>",
    "<NSAutoresizingMaskLayoutConstraint:0x755d5a0 h=--& v=--& UIView:0x9256a00.midX == + 160>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x9256c90 H:|-(NSSpace(20))-[UIView:0x9256a00]   (Names: '|':UIView:0x92557a0 )>

Break on objc_exception_throw to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKit/UIView.h> may also be helpful.
2013-07-25 10:47:30.567 neenah[1105:c07] Unable to simultaneously satisfy constraints.
    Probably at least one of the constraints in the following list is one you don't want. Try this: (1) look at each constraint and try to figure out which you don't expect; (2) find the code that added the unwanted constraint or constraints and fix it. (Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't understand, refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints) 
(
    "<NSLayoutConstraint:0x9256bb0 H:[UIView:0x9256a00]-(NSSpace(20))-|   (Names: '|':UIView:0x92557a0 )>",
    "<NSAutoresizingMaskLayoutConstraint:0x7561690 h=--- v=--- H:[UIWindow:0x92527c0(320)]>",
    "<NSAutoresizingMaskLayoutConstraint:0x755fe50 h=-&- v=-&- UIView:0x92557a0.width == UIWindow:0x92527c0.width>",
    "<NSAutoresizingMaskLayoutConstraint:0x755d690 h=--& v=--& H:[UIView:0x9256a00(320)]>",
    "<NSAutoresizingMaskLayoutConstraint:0x755d5a0 h=--& v=--& UIView:0x9256a00.midX == + 160>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x9256bb0 H:[UIView:0x9256a00]-(NSSpace(20))-|   (Names: '|':UIView:0x92557a0 )>

Break on objc_exception_throw to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKit/UIView.h> may also be helpful.

Answer 1

一些观察：

1. 你应该关闭translatesAutoresizingMaskIntoConstraints ：

    childviewcontroller.view.translatesAutoresizingMaskIntoConstraints = NO; 

2. 您也应该定义垂直约束：

    [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-[cview]-|" options:0 metrics:nil views:viewsDictionary]]; 

3. 与您的问题无关，您不需要为cview创建[[UIView alloc] init] 。 你立即丢弃它。

4. 我不确定你为什么要删除self.view的约束。 （我假设你这样做，因为你在测试中撕裂了你的头发。）你不必这样做。 但是如果你在这里有其他事情让你认为你需要这样做，那么让我们知道那是什么。

5. 添加子控制器时，调用didMoveToParentViewController ，而不是willMoveToParentViewController 。 addChildViewController为您调用willMoveToParentViewController 。 你只需要didMove...再现。

从而：

- (void)viewDidLoad {
    [super viewDidLoad];

    // instantiate the view controller

    ChildViewController *childViewController = [[ChildViewController alloc] initWithNibName:@"ChildViewController" bundle:nil];

    // or you can instantiate using storyboard
    //
    // ChildViewController *child = [self.storyboard instantiateViewControllerWithIdentifier:@"ChildIdentifier"];

    // now do the view controller containment calls to update the view controller hierarchy and add the view as appropriate

    [self addChildViewController:childViewController];
    childViewController.view.translatesAutoresizingMaskIntoConstraints = NO;
    [self.view addSubview:childViewController.view];
    [childViewController didMoveToParentViewController:self];
    UIView *childView = childViewController.view;

    NSDictionary *views = NSDictionaryOfVariableBindings(childView);
    [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-[childView]-|" options:0 metrics:nil views:views]];
    [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-[childView]-|" options:0 metrics:nil views:views]];
}