iOS 键盘动画冲突

Question

我目前正在编写一个 iOS 应用程序并遇到了一些动画问题。以下是显示我的问题的测试代码。这只是一个非常简单的动画，让 textField 在键盘显示时向上移动，在键盘隐藏时向下移动。有趣的是，如果是英文键盘，UIView 动画似乎与键盘动画有某种冲突，没有执行任何动画，但如果我切换到中文键盘，它就可以正常工作。我只是想确认它是否是来自苹果的错误....

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.

    UITextField *textField = [[UITextField alloc] init];
    self.textField = textField;
    textField.placeholder = @"Click me!!";
    textField.frame = CGRectMake(100, 350, 150, 40);
    [self.view addSubview:self.textField];
    self.textField.delegate = self;
}
-(BOOL)textFieldShouldBeginEditing:(UITextField *)textField
{
    [UIView animateWithDuration:0.25 animations:^{
        CGRect frame = self.textField.frame;
        frame.origin.y -= 100;
        self.textField.frame = frame;
    }];
    return YES;
}
-(BOOL)textFieldShouldReturn:(UITextField *)textField
{
    [self.textField resignFirstResponder];
    [UIView animateWithDuration:0.25 animations:^{
        CGRect frame = self.textField.frame;
        frame.origin.y += 100;
        self.textField.frame = frame;
    }];
    return YES;
}

更新

看来是苹果的bug...我尝试使用iOS 8.3模拟器，它运行 super 流畅...在iOS 9.3中，如果您只是尝试显示和隐藏键盘，即使不移动textField，动画多次操作后会卡住...

Answer 1

我建议您将动画 block 移动到通知中的方法 UIKeyboardWill{Show|Hide}Notification .文本字段的委托(delegate)方法询问文本字段及其行为——与键盘本身无关(您甚至可以 synchronize 持续时间、曲线和延迟)。

您正在向 -textFieldShouldReturn: 返回"is"这应该只检查文本字段是否应该处理返回键点击。

根据我对动画的经验，有时在使用真实设备进行测试时一切正常。我在此处进行了建议的更改，并且在 iPhone 5c (iOS 8.1) 和 iPhone 6s Plus (iOS 10, Beta 1) 上一切正常。

这是它的外观片段:

- (void)viewDidLoad {
    [super viewDidLoad];
    [self setupNotifications];
    [self initUIElements];
}

- (void)initUIElements {
    CGRect frame = CGRectMake(0.f, 20.f, 200.f, 44.f);
    self.textField = [[UITextField alloc] initWithFrame:frame];
    self.textField.center = CGPointMake(self.view.center.x, 32.f);
    self.textField.placeholder = @"Placeholder";
    self.textField.delegate = self;
    [self.view addSubview:self.textField];

    self.imageView = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, 50.f, 50.f)];
    self.imageView.center = self.view.center;
    self.imageView.backgroundColor = [UIColor magentaColor];
    [self.view addSubview:self.imageView];
}

- (void)setupNotifications {
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillHide:) name:UIKeyboardWillHideNotification object:nil];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillShow:) name:UIKeyboardWillShowNotification object:nil];
}

- (void)keyboardWillHide:(id)sender {
    [UIView animateWithDuration:1.f animations:^{
        self.textField.center = CGPointMake(self.view.center.x, 32.f);
        self.imageView.center = self.view.center;
    }];
}

- (void)keyboardWillShow:(id)sender {
    [UIView animateWithDuration:1.f animations:^{
        self.textField.center = CGPointMake(self.view.center.x, 62.f);
        self.imageView.center = CGPointMake(self.view.center.x, (self.view.center.y - 50.f));
    }];
}

- (BOOL)textFieldShouldReturn:(UITextField *)textField {
    [textField resignFirstResponder];
    return YES;
}