如何創建半透明模態UIViewController？

Question

我想創建一個可重用的UIViewController子類，它可以顯示為任何其他視圖控制器上的模態視圖控制器。 這個可重用的VC需要做的第一件事就是彈出一個UIActionSheet。 為此，我在VC中創建一個默認（空白）視圖以顯示來自的操作表。

但是，這看起來很糟糕，因為當彈出模態vc時，隱藏了父vc。 因此，看起來動作表漂浮在空白背景上。 如果動作表可能看起來彈出原始（父）vc會更好。

有沒有辦法實現這個目標？ 簡單地抓住父vc的視圖並從中激活UIActionSheet是否安全？

Answer 1

在您的模態視圖動畫后，它的大小將調整為與其父視圖相等。 你可以做的是在viewDidAppear：中，拍攝parentController的視圖，然后在你自己的視圖的子視圖列表后面插入一個包含父圖片的UIImageView：

#pragma mark -
#pragma mark Sneaky Background Image
- (void)viewDidAppear:(BOOL)animated {
    [super viewDidAppear:animated];

    // grab an image of our parent view
    UIView *parentView = self.parentViewController.view;

    // For iOS 5 you need to use presentingViewController:
    // UIView *parentView = self.presentingViewController.view;

    UIGraphicsBeginImageContext(parentView.bounds.size);
    [parentView.layer renderInContext:UIGraphicsGetCurrentContext()];
    UIImage *parentViewImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    // insert an image view with a picture of the parent view at the back of our view's subview stack...
    UIImageView *imageView = [[UIImageView alloc] initWithFrame:self.view.bounds];
    imageView.image = parentViewImage;
    [self.view insertSubview:imageView atIndex:0];
    [imageView release];
}

- (void)viewWillDisappear:(BOOL)animated {
    [super viewWillDisappear:animated];

    // remove our image view containing a picture of the parent view at the back of our view's subview stack...
    [[self.view.subviews objectAtIndex:0] removeFromSuperview];
}

Answer 2

您可以通過在父視圖中插入視圖來簡單地在父視圖控制器上顯示它。

像這樣的東西：

PseudoModalVC *vc = ...//initialization
vc.view.backgroundColor = [UIColor clearColor]; // like in previous comment, although you can do this in Interface Builder
vc.view.center = CGPointMake(160, -vc.view.bounds.size.height/2);
[parentVC.view addSubView:vc.view];

// animation for pop up from screen bottom
[UIView beginAnimation:nil context:nil];
vc.view.center = CGPointMake(160, vc.view.bounds.size.height/2);
[UIView commitAnimation];

Answer 3

是的。 將其添加到當前視圖控制器的視圖（或作為窗口的子視圖）並在屏幕上為其設置動畫，就像Valerii所說。

要用動畫刪除它，請執行此操作（我假設模態視圖為320 x 460，它將從屏幕滑下）：

- (void)dismissModal
{
    // animate off-screen
    [UIView beginAnimations:nil context:nil];
    [UIView setAnimationCurve:UIViewAnimationCurveEaseOut];
    [UIView setAnimationDuration:0.50];
    [UIView setAnimationDelegate:self];
    [UIView setAnimationDidStopSelector:@selector(animationDidStop:finished:context:)];

    self.view.frame = CGRectMake( 0, 480, 320, 460 );

    [UIView commitAnimations];
}

- (void)animationDidStop:(NSString *)animationID finished:(NSNumber *)finished context:(void *)context
{
    // don't remove until animation is complete. otherwise, the view will simply disappear
    [self.view removeFromSuperview];
}