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我的应用程序有一个密码视图，在概念上类似于 iOS 解锁屏幕。这是我在新 UIWindow 中呈现的 UIViewController。工作正常。我正在添加使用硬件键盘输入密码的功能。该keyCommands方法不会被调用，因此按键不会被识别，直到用户至少点击屏幕上的任意位置一次。它是一个全屏 UIWindow/UIViewController，所以大概是 UIWindow/UIViewController 中的一个点击。一旦点击发生，keyCommands将按预期调用，并且一切正常。我不想要求用户在输入密码之前点击他们的屏幕。

知道这里发生了什么，特别是为什么用户需要点击屏幕（以及如何避免这种要求）？

我已经通过包含重复的 NSTimer 调用来验证 UIViewController 是 firstResponder 。

- (void)viewDidAppear:(BOOL)animated {
    [super viewDidAppear:animated];
    [self becomeFirstResponder];
    [NSTimer scheduledTimerWithTimeInterval:0.5 repeats:YES block:^(NSTimer * _Nonnull timer) { //This is just debugging code!
        [self confirmFirstResponder];
    }];
}

-(BOOL)canBecomeFirstResponder {
    return YES;
}

-(void)confirmFirstResponder { //Caveman debugging at its finest
    if ([self isFirstResponder]) {
        NSLog(@"I'm first responder!"); //This is always logged repeatedly
    } else {
        NSLog(@"I'm NOT THE FIRST RESPONDER!!!!"); //This is never logged
    }
}

-(NSArray<UIKeyCommand *> *)keyCommands {
    NSLog(@"keyCommands fired"); //This is not fired until user taps the screen, then presses a key on the hardware keyboard
    NSArray<UIKeyCommand *> *commands = @[
        [UIKeyCommand commandWithTitle:@"1" image:nil action:@selector(buttonPressedWithKeyCommand:) input:@"1" modifierFlags:0 propertyList:nil],
        [UIKeyCommand commandWithTitle:@"2" image:nil action:@selector(buttonPressedWithKeyCommand:) input:@"2" modifierFlags:0 propertyList:nil],
        [UIKeyCommand commandWithTitle:@"3" image:nil action:@selector(buttonPressedWithKeyCommand:) input:@"3" modifierFlags:0 propertyList:nil],
        [UIKeyCommand commandWithTitle:@"4" image:nil action:@selector(buttonPressedWithKeyCommand:) input:@"4" modifierFlags:0 propertyList:nil],
        [UIKeyCommand commandWithTitle:@"5" image:nil action:@selector(buttonPressedWithKeyCommand:) input:@"5" modifierFlags:0 propertyList:nil],
        [UIKeyCommand commandWithTitle:@"6" image:nil action:@selector(buttonPressedWithKeyCommand:) input:@"6" modifierFlags:0 propertyList:nil],
        [UIKeyCommand commandWithTitle:@"7" image:nil action:@selector(buttonPressedWithKeyCommand:) input:@"7" modifierFlags:0 propertyList:nil],
        [UIKeyCommand commandWithTitle:@"8" image:nil action:@selector(buttonPressedWithKeyCommand:) input:@"8" modifierFlags:0 propertyList:nil],
        [UIKeyCommand commandWithTitle:@"9" image:nil action:@selector(buttonPressedWithKeyCommand:) input:@"9" modifierFlags:0 propertyList:nil],
        [UIKeyCommand commandWithTitle:@"0" image:nil action:@selector(buttonPressedWithKeyCommand:) input:@"0" modifierFlags:0 propertyList:nil],
        [UIKeyCommand commandWithTitle:@"Delete" image:nil action:@selector(buttonPressedWithKeyCommand:) input:@"\b" modifierFlags:0 propertyList:nil]
    ];
    return commands;
}

这是创建 UIWindow 的代码：

-(void)displayNewWindowWithViewController:(UIViewController *)vc {
    UINavigationController *nav=[[UINavigationController alloc] initWithRootViewController:vc]; //vc is the UIViewController containing the code above
    nav.navigationBarHidden=YES; //I have no recollection why I'm wrapping the vc in a UINavigationController...
    self.modalWindow = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
    self.modalWindow.backgroundColor = [UIColor whiteColor];
    self.modalWindow.clipsToBounds = NO;
    self.modalWindow.rootViewController = nav;
    self.modalWindow.windowLevel=99;
    [self makeKeyAndVisible:self.modalWindow];
}

-(void)makeKeyAndVisible:(UIWindow *)window {
    window.backgroundColor = [UIColor clearColor];
    window.frame=CGRectMake(0, [UIScreen mainScreen].bounds.size.height, window.frame.size.width, window.frame.size.height);
    [window makeKeyAndVisible];
    window.frame=CGRectMake(0, 0, window.frame.size.width, window.frame.size.height);
}

除了我要问的硬件键盘代码之外，我几乎七年前在这里写了所有东西。所以我不记得......任何事情的具体逻辑。我确实知道我使用了 UIWindow，因为这是一个安全视图，它绝对必须高于所有其他视图，包括应用程序可能在可见时添加的一些视图。理想与否，它一直在完美运行。如果需要进行实质性的重新架构以使硬件键盘在这里工作，那么硬件键盘功能将被丢弃。

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1 回答 1

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The new UIWindow wasn't quite the "key window" in terms of capturing keyboard events, even with the makeKeyandVisible instruction. I verified this by temporarily adding the same code to a UIViewController on the app's main UIWindow. It received the keyboard events until I tapped the screen (the new UIWindow).

I changed this:

[window makeKeyAndVisible]

to this:

window.hidden = NO;
dispatch_async(dispatch_get_main_queue(), ^{
    [window makeKeyWindow];
});

and suddenly the keyboard was fully captured by my new UIWindow.

I'm not quite sure what was going on. The original [window makeKeyAndVisible] was definitely running on the main thread (verified with [NSThread isMainThread]). But throwing it into another run loop did the trick. Go figure.

于 2021-03-02T02:53:34.633 回答