Question

我正在尝试创建一个简单的模态视图控制器，它允许您使用文本视图编辑文本。但是，当我以模态方式呈现视图控制器时，它从左下方向滑入而不是从底部滑入。

我的控制器只是监视键盘显示，然后使用自动布局适当调整文本视图的大小。这是代码：

#import "TextPicker.h"

@interface TextPicker ()

@property (weak, nonatomic) IBOutlet NSLayoutConstraint *keyboardHeight;

@end

@implementation TextPicker

- (id)initWithText:(NSString *)text
{
    UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"MainStoryboard_iPhone" bundle:nil];
    self = [storyboard instantiateViewControllerWithIdentifier:@"textPicker"];
    if (self) {
        self.text = text;

    }
    return self;
}

- (void)viewDidLoad
{
    [super viewDidLoad];

    [self observeKeyboard];

    //self.textView.text = self.text;
    [self.textView becomeFirstResponder];
}


- (void) viewWillDisappear:(BOOL)animated {
    [self.textView resignFirstResponder];
}

- (IBAction)savePressed:(id)sender {
    [self dismissViewControllerAnimated:YES completion:nil];    
}

- (IBAction)cancelPressed:(id)sender {
    [self dismissViewControllerAnimated:YES completion:nil];
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
}

- (void) dealloc {
    [self stopObervingKeyboard];
}

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

- (void)stopObervingKeyboard {
    [[NSNotificationCenter defaultCenter] removeObserver:self name:UIKeyboardWillChangeFrameNotification object:nil];
    [[NSNotificationCenter defaultCenter] removeObserver:self name:UIKeyboardWillHideNotification object:nil];
}

- (void)keyboardWillShow:(NSNotification *)notification {
    NSDictionary *info = [notification userInfo];

    NSValue *kbFrame = [info objectForKey:UIKeyboardFrameEndUserInfoKey];
    CGRect keyboardFrame = [kbFrame CGRectValue];
    self.keyboardHeight.constant = -keyboardFrame.size.height;

    NSTimeInterval animationDuration = [[info objectForKey:UIKeyboardAnimationDurationUserInfoKey] doubleValue];
    [UIView animateWithDuration:animationDuration animations:^{
        [self.view layoutIfNeeded];
    }];
}

- (void)keyboardWillHide:(NSNotification *)notification {
    NSDictionary *info = [notification userInfo];
    NSTimeInterval animationDuration = [[info objectForKey:UIKeyboardAnimationDurationUserInfoKey] doubleValue];

    self.keyboardHeight.constant = 0;
    [UIView animateWithDuration:animationDuration animations:^{
        [self.view layoutIfNeeded];
    }];
}

- (IBAction)dismissKeyboard:(id)sender {
    [self.textView resignFirstResponder];
}


@end

Answer 1

您的观点是通过将[self.view layoutIfNeeded]调用包装在动画块中而要求它来制作动画。

在viewDidLoad中，您开始观察键盘更改，当您检测到它们时，您可以对调整进行动画处理，这通常是正确的。但是，在视图执行第一个布局之前，您将显示键盘;这会生成从CGRectZero到适当大小的所有视图的动画。这就是你所看到的效果。

所以基本上你需要让视图在动画layoutIfNeeded调用之前布局。可能最简单的方法是将[self.textView becomeFirstResponder];移至viewWillAppear:或viewDidAppear:。

*作为旁注，记得打电话给超级外观。我注意到你没有打电话给[super viewWillDisappear];。

Present ViewController以模态方式显示奇怪的动画

1 个答案: