我正在尝试实现“将图像保存到库”功能，然后返回到当前的视图控制器，但是在新的iOS 13上，它又退回到显示当前视图的视图控制器：
PHPhotoLibrary.requestAuthorization({(_ status: PHAuthorizationStatus) -> Void in })
let shareItems: Array = [newImg,"Hello"] as [Any]
let activityController = UIActivityViewController(activityItems: shareItems, applicationActivities: nil)
if UIDevice.current.userInterfaceIdiom == .pad {
activityController.popoverPresentationController?.sourceView = saveButton
}
present(activityController, animated: true)
答案 0 :(得分：5)
我可以确认此错误仍在iOS 13.3.1中存在。以下解决方法是franze's solution的Swift版本。我更喜欢这种方法，因为它不会在视图控制器层次结构上做任何进一步的假设，并且不会使用方法混乱。
使用此附加UIWindow会中断iOS 12及更低版本上UIActivityViewController的 Cancel 按钮，因此我添加了对OS版本的检查。
private let activityWindow: UIWindow = {
let window = UIWindow(frame: UIScreen.main.bounds)
window.rootViewController = UIViewController()
return window
}()
func showActivityController() {
let activityViewController = UIActivityViewController(/* ... */)
activityViewController.completionWithItemsHandler = {
// ...
UIApplication.shared.delegate?.window??.makeKeyAndVisible()
}
// Use this workaround only on iOS 13
if ProcessInfo.processInfo.operatingSystemVersion.majorVersion == 13 {
activityWindow.makeKeyAndVisible()
activityWindow.rootViewController?.present(activityViewController, animated: true)
} else {
present(activityViewController, animated: true)
}
}
更新：显然，此解决方案在iPad上无法可靠运行。在iPad上，UIActivityViewController的显示方式似乎有所不同，并且只要在屏幕上可见，就不会记录任何触摸事件，从而有效地冻结了该应用程序。
答案 1 :(得分：4)
我生成了以下猴子补丁（由iOS 13.1.2检查）
- (void)export {
//
// ... Generate Your Activity Items ...
//
UIActivityViewController *activityViewController = [[UIActivityViewController alloc] initWithActivityItems:activityItems
applicationActivities:nil
completeBlock:^(NSError *activityError, BOOL completed) {
// Swizzling Dismiss Method
[[self class] switchInstanceMethodFrom:@selector(dismissViewControllerAnimated:completion:) To:@selector(lockedDismissViewControllerAnimated:completion:)];
}
];
// Swizzling Dismiss Method
[[self class] switchInstanceMethodFrom:@selector(dismissViewControllerAnimated:completion:) To:@selector(lockedDismissViewControllerAnimated:completion:)];
[self presentViewController:activityViewController animated:YES completion:nil];
}
- (void)lockedDismissViewControllerAnimated:(BOOL)flag completion:(void (^)(void))completion {
if ([self presentedViewController]) {
[self lockedDismissViewControllerAnimated:flag completion:completion];
}
}
// from http://qiita.com/paming/items/25eaf89e4f448ab05752
+(void)switchInstanceMethodFrom:(SEL)from To:(SEL)to
{
Method fromMethod = class_getInstanceMethod(self,from);
Method toMethod = class_getInstanceMethod(self,to );
method_exchangeImplementations(fromMethod, toMethod);
}
答案 2 :(得分：3)
@KDP解决方案的快速版本：
let fakeViewController = TransparentViewController()
fakeViewController.modalPresentationStyle = .overFullScreen
activityViewController.completionWithItemsHandler = { [weak fakeViewController] _, _, _, _ in
if let presentingViewController = fakeViewController?.presentingViewController {
presentingViewController.dismiss(animated: false, completion: nil)
} else {
fakeViewController?.dismiss(animated: false, completion: nil)
}
}
present(fakeViewController, animated: true) { [weak fakeViewController] in
fakeViewController?.present(activityViewController, animated: true, completion: nil)
}
fakeViewController要么由于活动完成而被撤消，要么我们需要在完成时将其撤消。
答案 3 :(得分：1)
这是我现在解决此错误的方法。我创建了一个伪造的视图控制器，并将其推入当前堆栈。看来UIActivityTypeSaveToCameraRoll取消了堆栈上的顶视图控制器，而其他选项则没有。如果活动类型不完整且UIActivityTypeSaveToCameraRoll，我会在完成模块中消除伪造的视图控制器。
typeof(self) __weak weakSelf = self;
[self.activityViewController setCompletionHandler:^(NSString *activityType, BOOL completed) {
if (activityType== UIActivityTypeSaveToCameraRoll && completed){
weakSelf.activityViewController = nil;
}
else{
[weakSelf dismissViewControllerAnimated:NO completion:nil];
weakSelf.activityViewController = nil;
}
}];
UIViewController *fakeVC=[[UIViewController alloc] init];
[self presentViewController:fakeVC animated:NO completion:^{
[fakeVC presentViewController:self.activityViewController animated:YES completion:nil];
}];
答案 4 :(得分：1)
- (UIWindow *)displayWindow
{
if (!_displayWindow)
{
_displayWindow = [[UIWindow alloc] initWithFrame:UIScreen.mainScreen.bounds];
_displayWindow.rootViewController = [[UIViewController alloc] init];
}
return _displayWindow;
}
- (void)showActivityController
{
UIActivityViewController *activityViewController = [[UIActivityViewController alloc] initWithActivityItems:@[] applicationActivities:nil];
activityViewController.completionWithItemsHandler = ^(UIActivityType __nullable activityType, BOOL completed, NSArray * __nullable returnedItems, NSError * __nullable activityError)
{
[UIApplication.sharedApplication.delegate.window makeKeyAndVisible];
};
[self.displayWindow makeKeyAndVisible];
[self.displayWindow.rootViewController presentViewController:activityViewController animated:true completion:nil];
}
确保_displayWindow是强引用。
答案 5 :(得分：0)
我通过将根视图控制器设置为当前窗口来解决此问题，我不知道为什么它会关闭当前视图控制器。我注意到，在iOS 13中展示新的视图控制器时，它将呈现为卡片堆叠样式，如果我在UIActivityController中选择了“保存图像”，则当前的视图控制器（卡片）将被关闭并显示以前的视图控制器。
答案 6 :(得分：0)
对于那些在iPad上屏幕冻结的人来说，这是一个简单的解决方案。它也可以在iPhone上使用。
func shareItems(_ sharedItems: [Any]) {
let activityViewController = UIActivityViewController(activityItems: sharedItems, applicationActivities: nil)
if let popoverController = activityViewController.popoverPresentationController {
popoverController.sourceRect = CGRect(x: UIScreen.main.bounds.width / 2, y: UIScreen.main.bounds.height / 2, width: 0, height: 0)
popoverController.sourceView = self.view
popoverController.permittedArrowDirections = UIPopoverArrowDirection(rawValue: 0)
}
self.present(activityViewController, animated: true, completion: nil)
}
答案 7 :(得分：0)
似乎它已在 iOS 14 中修复。对于旧版本，我发现通过使用空实现覆盖 dismiss(animated:) 方法更容易解决。见https://stackoverflow.com/a/66595125/2095408