Question

这是我挣扎了一段时间的一些代码。

如果您启动淡入动画，则标签文字会淡入。如果我开始淡出动画，标签文本会淡出。

当我启动startFade方法时，仅显示淡出。在启动fadeIn方法之前，如何等待fadeOut方法以可视方式完成。

-(IBAction)startFade:(id)sender{
    [self fadeIn];
    [self fadeOut];
}

-(IBAction)fadeIn:(id)sender{
    [self fadeIn];
}

-(IBAction)fadeOut:(id)sender{
[self fadeOut];
}

-(void) fadeIn{
    [_label setAlpha:0];
    [UILabel beginAnimations:NULL context:nil];
    [UILabel setAnimationDuration:2.0];
    [_label setAlpha:1];
    [UILabel commitAnimations];
}

-(void) fadeOut{
    [UILabel beginAnimations:NULL context:nil];
    [UILabel setAnimationDuration:2.0];
    [_label setAlpha:0];
    [UILabel commitAnimations];
}

Answer 1

当您像往常一样背靠背调用fadeIn和fadeOut方法时，代码会立即运行，因此您只能看到上一个调用方法的动画。基于UIView块的动画提供了一个完成处理程序，它似乎正是您正在寻找的。所以你的代码看起来像这样：

-(IBAction)startFade:(id)sender {

    [_label setAlpha:0.0f];        

    //fade in
    [UIView animateWithDuration:2.0f animations:^{

        [_label setAlpha:1.0f];

    } completion:^(BOOL finished) {

        //fade out
        [UIView animateWithDuration:2.0f animations:^{

            [_label setAlpha:0.0f];

        } completion:nil];

    }];
}

夫特：

@IBAction func startFade(_ sender: AnyObject) {

    label.alpha = 0.0

    // fade in
    UIView.animate(withDuration: 2.0, animations: { 
        label.alpha = 1.0
    }) { (finished) in
        // fade out
        UIView.animate(withDuration: 2.0, animations: {
            label.alpha = 0.0
        })
    }
}

Answer 2

为你做的工作（_label是你的标签）;

- (IBAction)startFade:(id)sender {
    [_label setAlpha:0.f];

    [UIView animateWithDuration:2.f delay:0.f options:UIViewAnimationOptionCurveEaseIn animations:^{
        [_label setAlpha:1.f];
    } completion:^(BOOL finished) {
        [UIView animateWithDuration:2.f delay:0.f options:UIViewAnimationOptionCurveEaseInOut animations:^{
            [_label setAlpha:0.f];
        } completion:nil];
    }];
}

Answer 3

试试这个..

//淡出

 -(void)fadeOut:(UIView*)viewToDissolve withDuration:(NSTimeInterval)duration   andWait:(NSTimeInterval)wait
{
[UIView beginAnimations: @"Fade Out" context:nil];

// wait for time before begin
[UIView setAnimationDelay:wait];

// druation of animation
[UIView setAnimationDuration:duration];
viewToDissolve.alpha = 0.0;
[UIView commitAnimations];
}

//淡入

-(void) fadeIn:(UIView*)viewToFadeIn withDuration:(NSTimeInterval)duration andWait:(NSTimeInterval)wait

{
[UIView beginAnimations: @"Fade In" context:nil];

// wait for time before begin
[UIView setAnimationDelay:wait];

    // druation of animation
[UIView setAnimationDuration:duration];
viewToFadeIn.alpha = 1;
[UIView commitAnimations];

}

//淡出淡出

-(void) fadeInFromFadeOut: (UIView*)viewToFadeIn withDuration:(NSTimeInterval)duration
{
    viewToFadeIn.hidden=NO;
    [self fadeOut:viewToFadeIn withDuration:1 andWait:0];
    [self fadeIn:viewToFadeIn withDuration:duration andWait:0];

}

//按钮操作

-(void) buttonClicked :(id)sender
{
   NSLog(@"Button clicked");

// Each button is given a tag
int tag = ((UIButton*)sender).tag;
if (tag ==1)
{
    sprite.alpha  =1;
    [self fadeOut : sprite withDuration: 10 andWait : 1 ];
}
else if (tag ==2)
{
    sprite.alpha  =0;
    [self fadeIn : sprite withDuration: 3 andWait : 1 ];
}
else
{
    [self fadeInFromFadeOut:sprite withDuration:10];
}
}

查看此link以下载示例..

请参阅此link。

很高兴与您分享..： - ）

Answer 4

通用答案：您可以使用此方法将动画应用于任何UIView对象。首先创建UIView类的扩展。创建一个单独的swift文件并编写如下代码

import Foundation
import UIKit

extension UIView {

  func fadeIn(){
    UIView.animateWithDuration(1.0, delay: 0.0, options: UIViewAnimationOptions.CurveEaseIn, animations: {
      self.alpha = 1.0
      }, completion: nil)
  }


  func fadeOut(){
    UIView.animateWithDuration(1.0, delay: 0.0, options: UIViewAnimationOptions.CurveEaseOut, animations: {
      self.alpha = 0.0
      }, completion: nil)
  }


}

这里的自我指的是你所指的任何UIView。您可以使用按钮，标签等来调用这两种方法。

然后在任何其他swift类中，你可以像这样调用fadeIn（）和fadeOut（）：

self.yourUIObject.fadeIn()
self.yourUIObject.fadeOut()

这为任何UIObject提供了所需的动画效果。

Answer 5

您可以执行以下操作（请在此处检查可能的参数值和类似方法： https://developer.apple.com/library/ios/documentation/uikit/reference/uiview_class/uiview/uiview.html

[UIView animateWithDuration:duration
                      delay:delay
                    options:option 
                 animations:^{
                     //fade in here (changing alpha of UILabel component)
                 } 
                 completion:^(BOOL finished){
                    if(finished){
                      //start a fade out here when previous animation is finished (changing alpha of UILabel component)
                 }];
}

Answer 6

基于@ holex的答案，但简化了一点（如评论所示）：

- (IBAction)startFade:(id)sender {
   [_label setAlpha:0.f];

   [UIView animateWithDuration:2.f 
                         delay:0.f 
                       options:UIViewAnimationOptionCurveEaseIn
                             | UIViewAnimationOptionAutoreverse 
                    animations:^{
                                  [_label setAlpha:1.f];
                                } 
                    completion:nil];
}

Answer 7

最简单的方法是使用：

[UIView animateWithDuration:(NSTimeInterval)duration animations:(void (^)(void))animations completion:(void (^)(BOOL finished))completion]

并将fadeOut调用添加到completion块。 The documentation可能有助于回答您的任何问题。

如果由于某种原因无法使用块版本，那么您必须设置委托将响应的委托（[UIView setAnimationDelegate:(id)delegate]）和选择器（[UIView setAnimationDidStopSelector:]）。

再次，请参阅the documentation了解详情。

Answer 8

我的任务是让标签淡出。然后用改变后的文字淡入淡出。解决方案是：

    -(void)performAnimationOnHistoryButtonLabelUpdatingTextTo:(NSString *)text
{
    [UIView animateWithDuration:0.4f animations:^{
        [self.historyButtonLabel setAlpha:0.0f];

    } completion:^(BOOL finished) {
        self.historyButtonLabel.text = text;

        [UIView animateWithDuration:0.4f animations:^{
            [self.historyButtonLabel setAlpha:1.0f];
        } completion:nil];

    }];
}

Answer 9

labelAnimate = (UILabel*) [self.view viewWithTag:101];
btnTapMe = (UIButton*) [self.view viewWithTag:100];
[btnTapMe addTarget:self action:@selector(startAnimating:) forControlEvents:UIControlEventTouchUpInside];

//////////////

-(void) startAnimating:(UIButton*)button {
    [labelAnimate setAlpha:0.0];
    [NSTimer scheduledTimerWithTimeInterval:1.8 target:self selector:@selector(continuousEaseInOut) userInfo:button repeats:YES];
}

-(void) continuousFadeInOut {
    [UIView animateWithDuration:2.0 delay:0.0 options:UIViewAnimationOptionCurveEaseIn animations:^{
        [labelAnimate setAlpha:1.0];
    } completion:^(BOOL finished) {
        [UIView animateWithDuration:2.0 delay:0.0 options:UIViewAnimationOptionCurveEaseInOut animations:^{
            [labelAnimate setAlpha:0.0];
        } completion:nil];
    }];
}

Answer 10

我强烈建议您使用通用实现，以便在需要淡入淡出效果时重复使用代码。

您应该创建UIView扩展程序：

UIView+Animations.h

#import <Foundation/Foundation.h>

@interface UIView (Animations)

- (void)fadeInWithCompletion:(void (^ __nullable)(BOOL finished))completion;
- (void)fadeOutWithCompletion:(void (^ __nullable)(BOOL finished))completion;;

@end

UIView+Animations.m

#import "UIView+Animations.h"

@implementation UIView (Animations)

- (void)fadeInWithCompletion:(void (^ __nullable)(BOOL finished))completion {
    [UIView animateWithDuration:2 animations:^{
        [self setAlpha:1];
    } completion:completion];
}

- (void)fadeOutWithCompletion:(void (^ __nullable)(BOOL finished))completion {
    [UIView animateWithDuration:2 animations:^{
        [self setAlpha:0];
    } completion:completion];
}

@end

因此，您只需将新文件导入到您的班级或Prefix.pch内，并按照以下方式使用：

[_label fadeOutWithCompletion:^(BOOL finished) {
   [_label fadeInWithCompletion:nil];
}];

请注意，在完成后无其他任何操作时，您也可以使用nil作为完成参数。

我还建议您不要参数化持续时间以保持整个应用程序的模式。

此实现可以在将来用于UIButton，UILabel，UITextField ......好吧，任何来自UIView的类。

Answer 11

快捷键4 如果单击按钮时仅需要一个脉冲，请使用：

@IBAction func didPressButton(_ sender: UIButton) {
        self.someView.alpha = 0
        UIView.animate(withDuration: 0.4,
                       delay: 0,
                       options: [.curveEaseInOut, .autoreverse],
                       animations: {
                        self.someView.alpha = 1
        },
                       completion: { _ in
                        self.someView.alpha = 0
        })
    }

Answer 12

可以使用UIView.animate(withDuration: animations:)

组合淡入和淡出动画

UIView.animate(withDuration: animationDuration, animations: {
            myView.alpha = 0.75
            myView.alpha = 1.0
        })

Answer 13

Swift 5版本的iPhoneDeveloper的答案：

extension UIView {

func fadeIn() {
    UIView.animate(withDuration: 1.0, delay: 0.0, options: UIView.AnimationOptions.curveEaseIn, animations: {
        self.alpha = 1.0
    }, completion: nil)
}


func fadeOut() {
    UIView.animate(withDuration: 1.0, delay: 0.0, options: UIView.AnimationOptions.curveEaseOut, animations: {
        self.alpha = 0.0
    }, completion: nil)
}

}

淡出淡出动画

13 个答案: