如何使子视图居中

Question

我将UIViewController子视图添加到另一个UIViewController。

效果很好。但是我很难尝试将子视图置于父视图的中间位置。

我读了，我找到了两行代码，但对我来说不起作用。

有人能指出我的问题吗？

那些是：

popupController.view.center = [self.view convertPoint:self.view.center fromView:self.view.superview];

和

popupController.view.center = CGPointMake(self.view.bounds.size.width / 2, self.view.bounds.size.height / 2);

父视图控制器代码：

- (IBAction)selectRoutine:(id)sender {
    UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"Storyboard" bundle:nil];

    createRoutinePopupViewController* popupController = [storyboard instantiateViewControllerWithIdentifier:@"createRoutinePopupView"];
   // popupController.view.center = [self.view convertPoint:self.view.center fromView:self.view.superview];
    popupController.view.center = CGPointMake(self.view.bounds.size.width / 2, self.view.bounds.size.height / 2);

    //Tell the operating system the CreateRoutine view controller
    //is becoming a child:
    [self addChildViewController:popupController];

    //add the target frame to self's view:
    [self.view addSubview:popupController.view];

    //Tell the operating system the view controller has moved:
    [popupController didMoveToParentViewController:self];


}

儿童设置

Answer 1

看起来像是在居中后重新定位视图控制器视图。可能在didMoveToParentViewController:。

将居中代码移至selectRoutine:方法

的末尾

- (IBAction)selectRoutine:(id)sender
{
    UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"Storyboard" bundle:nil];

    createRoutinePopupViewController* popupController = [storyboard instantiateViewControllerWithIdentifier:@"createRoutinePopupView"];

    [self addChildViewController:popupController];
    [self.view addSubview:popupController.view];
    [popupController didMoveToParentViewController:self];

    //do the centering here
    popupController.view.center = [self.view convertPoint:self.view.center fromView:self.view.superview];

}

或者更好的是，将其移至didMoveToParentViewController:

- (void)didMoveToParentViewController:(UIViewController *)parent
{
    //whatever code you have here

    self.view.center = self.view.superview.center;
}

可能您需要稍微修改此代码。但我确定你的问题是不正确的（执行时间）放置中心代码 - 随后被其他一些视图定位覆盖。

Answer 2

为了将子视图移动到视图中心，我尝试了这个

YourView.center = CGPointMake(self.view.center.x,self.view.center.y);

Answer 3

此处发布的解决方案适合我。通常，如果您希望微调器介于UIAlertController消息（通常位于UIAlertController的中心）和下面的任何操作按钮（如Ok或取消）之间，请稍微调整它的高度

spinnerIndicator.center = CGPointMake(self.superview.view.bounds.width / 2,
            (self.alertVC.view.bounds.height / 2) * 1.07)
// The superview of the spinnerIndictator here is the UIAlertController. 

根据我的实验，比率1.07将微调器放在所有可用iPhone屏幕下方的消息和操作按钮之间。