如何在模态视图控制器中使用UIBlurEffect？ [英] How to use UIBlurEffect with modal View Controllers?

问题描述

我有一个 UIViewController ，它以模态方式呈现另一个 UIViewController 。我希望模态视图控制器具有iOS 7引入的模糊/透明度。我尝试使用新的 UIVisualEffect ，但似乎只适用于 UIViews ，而不是 UIViewControllers ？

I have a UIViewController that presents another UIViewController modally. I want the modal view controller to have the blur/transparency that iOS 7 introduced. I tried using the new UIVisualEffect but it seems like that only works with UIViews, and not UIViewControllers?

这是我写的代码，我作为子视图添加的所有视图都是我想要的在它下面的模糊视图上方的用户界面。

Here is the code I've written, all the views I've added as subviews are what I want to be in the user interface above the blurred out view below it.

在呈现视图控制器中，我在应用模糊之前拍摄了我传递给模态视图控制器的屏幕截图。

In the presenting view controller, I take a screenshot of the screen that I pass to the modal view controller before applying the blur.

在呈现视图控制器时：

- (UIImage *)viewImage {
    CGSize size = CGSizeMake(self.view.frame.size.width,self.view.frame.size.height);
    UIGraphicsBeginImageContext(size);
    [self.view drawViewHierarchyInRect:(CGRect){CGPointZero, self.view.frame.size.width, self.view.frame.size.height} afterScreenUpdates:YES];
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    return image;
}

在模态视图控制器中：

- (void)viewDidLoad {
    [super viewDidLoad];

    [self.view addSubview:[[UIImageView alloc] initWithImage:self.backgroundImage]];
    //self.backgroundImage is the image that the method above returns, it's a screenshot of the presenting view controller.
    UIBlurEffect *blurEffect = [UIBlurEffect effectWithStyle:UIBlurEffectStyleLight];
    UIVisualEffectView *blurEffectView = [[UIVisualEffectView alloc] initWithEffect:blurEffect];
    [blurEffectView setFrame:self.view.bounds];
    [self.view addSubview:blurEffectView];

    [self.view bringSubviewToFront:self.cancelButton];
    [self.view bringSubviewToFront:self.titleLabel];
    [self.view bringSubviewToFront:self.tableView];
}

推荐答案

使用UIVisualEffectView时，你不要不需要生成快照。尝试删除 - （UIImage *）viewImage并在模型视图控制器中添加一个大小与视图控制器视图匹配的UIVisualEffectView，并将所有控制视图添加到UIVisualEffectView的contentView中。

When using UIVisualEffectView, you don't need to generate a snapshot. Try removing "- (UIImage *)viewImage" and in the model view controller add a UIVisualEffectView with size matching the view controller view, and add all "control" views into the UIVisualEffectView's contentView.

- (void)viewDidLoad {
    [super viewDidLoad];

    UIBlurEffect *blurEffect = [UIBlurEffect effectWithStyle:UIBlurEffectStyleLight];
    UIVisualEffectView *blurEffectView = [[UIVisualEffectView alloc] initWithEffect:blurEffect];
    [blurEffectView setFrame:self.view.bounds];
    [self.view addSubview:blurEffectView];

    [blurEffectView.contentView addSubview:self.cancelButton];
    [blurEffectView.contentView addSubview:self.titleLabel];
    [blurEffectView.contentView addSubview:self.tableView];
}

https://developer.apple.com/library/prerelease/ios/documentation/UIKit/Reference/UIVisualEffectView/index.html

我没有尝试使用故事板，但这是一个经过测试的工作片段。可能是一个好的开始。转换为objc应该是非常直接的

I haven't tried it with storyboards, but here's a tested working snippet. Might be a good place to start. Translating to objc should be pretty straightfoward

这是呈现视图控制器

import UIKit

class BaseViewController: UIViewController {

init(nibName nibNameOrNil: String?, bundle nibBundleOrNil: NSBundle?) {
    super.init(nibName: nibNameOrNil, bundle: nibBundleOrNil)
}

override func viewDidLoad() {
    super.viewDidLoad()

    var backgroundImage = UIImageView(image: UIImage(named: "image"))
    self.view.addSubview(backgroundImage)

    var button = UIButton(frame: CGRectMake(0, 100, 320, 50))
    button.setTitle("Lorem Ipsum", forState: UIControlState.Normal)
    button.backgroundColor = UIColor.redColor()
    button.addTarget(self, action: "onButtonTapped:", forControlEvents: UIControlEvents.TouchUpInside)

    self.view.addSubview(button)
}

func onButtonTapped(sender: UIButton?) {
    var modal = ModalViewController(nibName: nil, bundle: nil)
    modal.modalPresentationStyle = UIModalPresentationStyle.OverCurrentContext
    self.presentViewController(modal, animated: true, completion: {})
}
}

这是模态

import UIKit

class ModalViewController: UIViewController {

init(nibName nibNameOrNil: String?, bundle nibBundleOrNil: NSBundle?) {
    super.init(nibName: nibNameOrNil, bundle: nibBundleOrNil)
}

override func viewDidLoad() {
    super.viewDidLoad()

    self.view.backgroundColor = UIColor.clearColor()

    let effect = UIBlurEffect(style: UIBlurEffectStyle.Light)
    let blurView = UIVisualEffectView(effect: effect)

    blurView.frame = self.view.bounds

    self.view.addSubview(blurView)
}
}

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