如何同时解除UIAlertController和键盘? [英] How to dismiss an UIAlertController and the keyboard simultaneously?
问题描述
我创建了一个带有 UIAlertController
的注册表单,并使用方法 addTextFieldWithConfigurationHandler
添加文本字段。但是有一点问题。
I have created a signup form with a UIAlertController
and used the method addTextFieldWithConfigurationHandler
to add a text field. But there is a little problem.
当表单出现时,键盘和模态会显示一个平滑的动画。关闭表单时,模式首先消失 ,然后键盘消失。这使键盘突然下降。
When the form shows up, the keyboard and modal appear with a smooth animation. When closing the form, the modal disappears first, and then the keyboard disappears. This makes the keyboard make a sudden downward fall.
如何使模态和键盘优雅地消失?
How can I make the modal and keyboard graciously disappear?
lazy var alertController: UIAlertController = { [weak self] in
let alert = UIAlertController(title: "Alert", message: "This is a demo alert", preferredStyle: .Alert)
alert.addTextFieldWithConfigurationHandler { textField in
textField.delegate = self
}
alert.addAction(UIAlertAction(title: "OK", style: .Default, handler: nil))
return alert
}()
@IBAction func alert() {
presentViewController(alertController, animated: true, completion: nil)
}
func textFieldShouldReturn(textField: UITextField) -> Bool {
alertController.dismissViewControllerAnimated(true, completion: nil)
return true
}
推荐答案
您可以将视图控制器或其他对象设置为转换UIAlertController的委托( alert.transitioningDelegate
)并制作自定义动画以解除。
代码示例:
You can set your view controller or other object as transitioning delegate of your UIAlertController (alert.transitioningDelegate
) and make a custom animation for dismissing.
Code sample:
@interface ViewController () <UIViewControllerTransitioningDelegate, UIViewControllerAnimatedTransitioning, UITextFieldDelegate>
@property (assign, nonatomic) NSTimeInterval keyboardAnimationDuration;
@property (assign, nonatomic) CGFloat keyboardHeight;
@property (nonatomic, strong) UIAlertController *alertController;
@property (nonatomic,strong) id <UIViewControllerTransitioningDelegate> transitioningDelegateForAlertController;
@end
@implementation ViewController
- (void)dealloc {
[[NSNotificationCenter defaultCenter] removeObserver:self];
}
- (void)viewDidLoad {
[super viewDidLoad];
[self subscribeForKeyboardNotification];
}
#pragma mark - Keyboard notifications
- (void)subscribeForKeyboardNotification {
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(keyboardWillAppear:)
name:UIKeyboardWillShowNotification
object:nil];
}
- (void)keyboardWillAppear:(NSNotification *)notification {
self.keyboardAnimationDuration = [notification.userInfo[UIKeyboardAnimationDurationUserInfoKey] doubleValue];
self.keyboardHeight = [notification.userInfo[UIKeyboardFrameEndUserInfoKey] CGRectValue].size.height;
}
#pragma mark - IBAction
- (IBAction)showAlertButtonPressed:(id)sender {
[self showAlert];
}
- (void)showAlert {
self.alertController = [UIAlertController alertControllerWithTitle:@"Alert"
message:@"This is a demo alert"
preferredStyle:UIAlertControllerStyleAlert];
__weak typeof(self) weakSelf = self;
[self.alertController addTextFieldWithConfigurationHandler:^(UITextField *textField) {
textField.delegate = weakSelf;
}];
self.transitioningDelegateForAlertController = self.alertController.transitioningDelegate;
self.alertController.transitioningDelegate = self;
[self.alertController addAction:[UIAlertAction actionWithTitle:@"Ok"
style:UIAlertActionStyleCancel
handler:nil]];
[self presentViewController:self.alertController animated:YES completion:nil];
}
#pragma mark - UITextFieldDelegate
- (BOOL)textFieldShouldReturn:(UITextField *)textField {
[self.alertController dismissViewControllerAnimated:YES completion:nil];
return YES;
}
#pragma mark - UIViewControllerTransitioningDelegate
- (id <UIViewControllerAnimatedTransitioning>)animationControllerForPresentedController:(UIViewController *)presented
presentingController:(UIViewController *)presenting
sourceController:(UIViewController *)source {
return [self.transitioningDelegateForAlertController animationControllerForPresentedController:presented
presentingController:presenting
sourceController:source];
}
- (id <UIViewControllerAnimatedTransitioning>)animationControllerForDismissedController:(UIViewController *)dismissed {
return self;
}
#pragma mark - UIViewControllerAnimatedTransitioning
- (NSTimeInterval)transitionDuration:(id <UIViewControllerContextTransitioning>)transitionContext {
return self.keyboardAnimationDuration ?: 0.5;
}
- (void)animateTransition:(id <UIViewControllerContextTransitioning>)transitionContext {
UIViewController *destination = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
if ([destination isBeingPresented])
[self animatePresentation:transitionContext];
else
[self animateDismissal:transitionContext];
}
- (void)animatePresentation:(id <UIViewControllerContextTransitioning>)transitionContext {
NSTimeInterval transitionDuration = [self transitionDuration:transitionContext];
UIViewController *fromController = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
UIViewController *toController = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
UIView *container = transitionContext.containerView;
fromController.view.frame = container.bounds;
toController.view.frame = container.bounds;
toController.view.alpha = 0.0f;
[container addSubview:toController.view];
[fromController beginAppearanceTransition:NO animated:YES];
[UIView animateWithDuration:transitionDuration
animations:^{
toController.view.alpha = 1.0;
}
completion:^(BOOL finished) {
[fromController endAppearanceTransition];
[transitionContext completeTransition:YES];
}];
}
- (void)animateDismissal:(id <UIViewControllerContextTransitioning>)transitionContext {
NSTimeInterval transitionDuration = [self transitionDuration:transitionContext];
UIViewController *fromController = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
UIViewController *toController = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
[toController beginAppearanceTransition:YES animated:YES];
[UIView animateWithDuration:transitionDuration
animations:^{
fromController.view.alpha = 0.0;
[fromController.view endEditing:YES];
CGRect frame = fromController.view.frame;
frame.origin.y += self.keyboardHeight / 2;
fromController.view.frame = frame;
}
completion:^(BOOL finished) {
[toController endAppearanceTransition];
[transitionContext completeTransition:YES];
}];
}
@end
结果:
PS:我使用旧警报转换委托进行演示,因为我无法重现原始动画。所以 animatePresentation:
方法永远不会被使用。
P.S.: I used old alert's transitioning delegate for presentation because I can't reproduce an original animation. So animatePresentation:
method is never used.
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