如何更改UIAlertController的背景颜色？

Question

由于UIActionSheet在iOS 8中的奇怪行为，我已经将UIAlertController与UIAction一起实现为按钮。我想改变UIAlertController的整个背景。但我找不到任何办法。

甚至尝试过，

actionController.view.backgroundColor = [UIColor blackColor];

但是没有帮助我。关于这方面的任何意见都是值得注意的。

提前致谢。

Answer 1

你必须深入了解一些观点：

let subview = actionController.view.subviews.first! as UIView
let alertContentView = subview.subviews.first! as UIView
alertContentView.backgroundColor = UIColor.blackColor()

也许你想保持原来的角半径：

 alertContentView.layer.cornerRadius = 5;

对不起“Swifting”，但我不熟悉Objective-C。我希望这是类似的。

当然，更改动作的标题颜色也很重要。不幸的是我不知道，如何分别设置动作的颜色。但是，这是如何更改所有按钮文本颜色：

actionController.view.tintColor = UIColor.whiteColor();

编辑：

自这个答案发布以来，UIAlertController的角半径已经改变了！替换这个：

 alertContentView.layer.cornerRadius = 5;

对此：

 actionContentView.layer.cornerRadius = 15

Answer 2

您可以使用外观代理。

[[UIView appearanceWhenContainedIn:[UIAlertController class], nil] setBackgroundColor:[UIColor blackColor]];

这似乎适用于除了作为动作表提交时的取消操作。

Answer 3

也许你喜欢在黑暗模式下使用模糊效果。这是一个非常简单的方法：

UIVisualEffectView.appearance(whenContainedInInstancesOf: [UIAlertController.classForCoder() as! UIAppearanceContainer.Type]).effect = UIBlurEffect(style: .dark)

Answer 4

我找到了一种破解方法。首先，您需要一个扩展名，以便您在UIVisualEffectView中搜索UIAlertController：

extension UIView
{
    func searchVisualEffectsSubview() -> UIVisualEffectView?
    {
        if let visualEffectView = self as? UIVisualEffectView
        {
            return visualEffectView
        }
        else
        {
            for subview in subviews
            {
                if let found = subview.searchVisualEffectsSubview()
                {
                    return found
                }
            }
        }

        return nil
    }
}

重要提示：调用presentViewController后必须调用此函数，因为只有在加载视图控制器后才能将视觉效果视图插入到位。然后，您可以将与其关联的效果更改为暗模糊效果：

self.presentViewController(actionController, animated: true, completion: nil)

if let visualEffectView = actionController.view.searchVisualEffectsSubview()
{
    visualEffectView.effect = UIBlurEffect(style: .Dark)
}

这是最终的结果：

老实说我很惊讶它的工作原理！我想这可能是Apple忘记添加的内容。此外，我还没有通过批准通过这个“黑客”（它不是黑客，因为我们只使用公共API），但我相信不会有问题。

Answer 5

对于Swift 3 / Swift 4

let subview =(alert.view.subviews.first?.subviews.first?.subviews.first!)! as UIView

            subview.backgroundColor = UIColor(red: (145/255.0), green: (200/255.0), blue: (0/255.0), alpha: 1.0)

            alert.view.tintColor = UIColor.black

。

Answer 6

Swift3

再加上一层与swift2比较

    let subview1 = alert.view.subviews.first! as UIView
    let subview2 = subview1.subviews.first! as UIView
    let view = subview2.subviews.first! as UIView

    subview.backgroundColor = backgroundColor
    view.backgroundColor = backgroundColor
    view.layer.cornerRadius = 10.0

    // set color to UILabel font
    setSubviewLabelsToTextColor(textColor, view: view)

    // set font to alert via KVC, otherwise it'll get overwritten
    let titleAttributed = NSMutableAttributedString(
        string: alert.title!,
        attributes: [NSFontAttributeName:UIFont.boldSystemFont(ofSize: 17)])
    alert.setValue(titleAttributed, forKey: "attributedTitle")

    let messageAttributed = NSMutableAttributedString(
        string: alert.message!,
        attributes: [NSFontAttributeName:UIFont.systemFont(ofSize: 13)])
    alert.setValue(messageAttributed, forKey: "attributedMessage")

    // set the buttons to non-blue, if we have buttons
    if let buttonColor = buttonColor {
        alert.view.tintColor = buttonColor
    }

Answer 7

这是一个适用于iPad和iPhone的UIAlertController扩展。取决于所选的blurStyle，取消按钮将自动从深色变为白色：

extension UIAlertController {

    private struct AssociatedKeys {
        static var blurStyleKey = "UIAlertController.blurStyleKey"
    }

    public var blurStyle: UIBlurEffectStyle {
        get {
            return objc_getAssociatedObject(self, &AssociatedKeys.blurStyleKey) as? UIBlurEffectStyle ?? .extraLight
        } set (style) {
            objc_setAssociatedObject(self, &AssociatedKeys.blurStyleKey, style, .OBJC_ASSOCIATION_RETAIN_NONATOMIC)

            view.setNeedsLayout()
            view.layoutIfNeeded()
        }
    }

    public var cancelButtonColor: UIColor? {
        return blurStyle == .dark ? UIColor(red: 28.0/255.0, green: 28.0/255.0, blue: 28.0/255.0, alpha: 1.0) : nil
    }

    private var visualEffectView: UIVisualEffectView? {
        if let presentationController = presentationController, presentationController.responds(to: Selector(("popoverView"))), let view = presentationController.value(forKey: "popoverView") as? UIView // We're on an iPad and visual effect view is in a different place.
        {
            return view.recursiveSubviews.flatMap({$0 as? UIVisualEffectView}).first
        }

        return view.recursiveSubviews.flatMap({$0 as? UIVisualEffectView}).first
    }

    private var cancelActionView: UIView? {
        return view.recursiveSubviews.flatMap({
            $0 as? UILabel}
        ).first(where: {
            $0.text == actions.first(where: { $0.style == .cancel })?.title
        })?.superview?.superview
    }

    public convenience init(title: String?, message: String?, preferredStyle: UIAlertControllerStyle, blurStyle: UIBlurEffectStyle) {
        self.init(title: title, message: message, preferredStyle: preferredStyle)
        self.blurStyle = blurStyle
    }

    open override func viewWillLayoutSubviews() {
        super.viewWillLayoutSubviews()

        visualEffectView?.effect = UIBlurEffect(style: blurStyle)
        cancelActionView?.backgroundColor = cancelButtonColor
    }
}

还需要以下UIView扩展：

extension UIView {

    var recursiveSubviews: [UIView] {
        var subviews = self.subviews.flatMap({$0})
        subviews.forEach { subviews.append(contentsOf: $0.recursiveSubviews) }
        return subviews
    }
}

例：

let controller = UIAlertController(title: "Dark Alert Controller", message: nil, preferredStyle: .actionSheet, blurStyle: .dark)

// Setup controller actions etc...

present(controller, animated: true, completion: nil)

苹果手机：

iPad的：

Answer 8

func Alert(View: ViewController, Title: String, TitleColor: UIColor, Message: String, MessageColor: UIColor, BackgroundColor: UIColor, BorderColor: UIColor, ButtonColor: UIColor) {

    let TitleString = NSAttributedString(string: Title, attributes: [NSFontAttributeName : UIFont.systemFontOfSize(15), NSForegroundColorAttributeName : TitleColor])
    let MessageString = NSAttributedString(string: Message, attributes: [NSFontAttributeName : UIFont.systemFontOfSize(15), NSForegroundColorAttributeName : MessageColor])

    let alertController = UIAlertController(title: Title, message: Message, preferredStyle: .Alert)

    alertController.setValue(TitleString, forKey: "attributedTitle")
    alertController.setValue(MessageString, forKey: "attributedMessage")

    let okAction = UIAlertAction(title: "OK", style: .Default) { (action) in

    }

    let cancelAction = UIAlertAction(title: "Cancel", style: .Default, handler: nil)

    alertController.addAction(okAction)
    alertController.addAction(cancelAction)


    let subview = alertController.view.subviews.first! as UIView
    let alertContentView = subview.subviews.first! as UIView
    alertContentView.backgroundColor = BackgroundColor
    alertContentView.layer.cornerRadius = 10
    alertContentView.alpha = 1
    alertContentView.layer.borderWidth = 1
    alertContentView.layer.borderColor = BorderColor.CGColor


    //alertContentView.tintColor = UIColor.whiteColor()
    alertController.view.tintColor = ButtonColor

    View.presentViewController(alertController, animated: true) {
        // ...
    }
}

Answer 9

对于Objective - C Code可能是喜欢的。

UIAlertController * alert=[UIAlertController alertControllerWithTitle:@"Title"
                                                              message:@"Message"
                                                       preferredStyle:UIAlertControllerStyleAlert];
UIView *firstSubview = alert.view.subviews.firstObject;
UIView *alertContentView = firstSubview.subviews.firstObject;
for (UIView *subSubView in alertContentView.subviews) {
    subSubView.backgroundColor = [UIColor colorWithRed:255/255.0f green:255/255.0f blue:255/255.0f alpha:1.0f];
}
UIAlertAction *cancelAction = [UIAlertAction actionWithTitle:@"Cancel" style:UIAlertActionStyleDefault handler:^(UIAlertAction * action){
   //Close Action
}];
[alert addAction:cancelAction];
[self presentViewController:alert animated:YES completion:nil];

Answer 10

我找到的最佳决定（两侧没有白点）

Link to original answer的Vadim Akhmerov

回答：

将UIAlertController子类化更容易。

这个想法是每次调用viewDidLayoutSubviews时遍历视图层次结构，删除UIVisualEffectView的效果并更新它们的backgroundColor：

class AlertController: UIAlertController {

    /// Buttons background color.
    var buttonBackgroundColor: UIColor = .darkGray {
        didSet {
            // Invalidate current colors on change.
            view.setNeedsLayout()
        }
    }

    override func viewDidLayoutSubviews() {
        super.viewDidLayoutSubviews()

        // Traverse view hierarchy.
        view.allViews.forEach {
            // If there was any non-clear background color, update to custom background.
            if let color = $0.backgroundColor, color != .clear {
                $0.backgroundColor = buttonBackgroundColor
            }
            // If view is UIVisualEffectView, remove it's effect and customise color.
            if let visualEffectView = $0 as? UIVisualEffectView {
                visualEffectView.effect = nil
                visualEffectView.backgroundColor = buttonBackgroundColor
            }
        }

        // Update background color of popoverPresentationController (for iPads).
        popoverPresentationController?.backgroundColor = buttonBackgroundColor
    }

}


extension UIView {

    /// All child subviews in view hierarchy plus self.
    fileprivate var allViews: [UIView] {
        var views = [self]
        subviews.forEach {
            views.append(contentsOf: $0.allViews)
        }

        return views
    }

}

用法：

1. 创建警报控制器（现在使用AlertController而不是UIAlertController）

让testAlertController = AlertController（title：nil，message：nil，preferredStyle：.actionSheet）

2. 在自定义类“AlertController”上设置背景颜色：

var buttonBackgroundColor：UIColor = .darkGray