Ios UIView图像-从一个图像淡入另一个图像

我正在尝试使用单个UIView从一个图像淡入另一个图像（是的！已经在stackoverflow上看到了Q&a，它使用两个UIView-彼此重叠）

我有一个当前的UIView图像，希望淡出并替换为另一个图像，然后淡入新图像。

我试过以下几点：第一个的褪色，独自一人，有效

尝试#1）

这会在新的图像中消失。。。旧图像不会褪色。还尝试在两组代码之间“暂停”

尝试#2）

这会立即显示新图像，不会褪色或“交叉溶解”

尝试#3）

这与#2的结果相同

---

知道怎么回事吗？

试试这个。它淡出图像，交换没有动画的图像，然后淡入另一个动画

CGFloat fadeDuration = 0.5f;
[UIView animateWithDuration:fadeDuration animations:^{
    [_imgMirror setAlpha:0.0];
} completion:^(BOOL finished) {
    UIImage * toImage = [UIImage imageNamed:@"NewImage"];
    _imgMirror.image = toImage;
    [UIView animateWithDuration:fadeDuration animations:^{
        [_imgMirror setAlpha:1.0];
    }];
}];

---

试试这个。它淡出图像，交换没有动画的图像，然后淡入另一个动画

CGFloat fadeDuration = 0.5f;
[UIView animateWithDuration:fadeDuration animations:^{
    [_imgMirror setAlpha:0.0];
} completion:^(BOOL finished) {
    UIImage * toImage = [UIImage imageNamed:@"NewImage"];
    _imgMirror.image = toImage;
    [UIView animateWithDuration:fadeDuration animations:^{
        [_imgMirror setAlpha:1.0];
    }];
}];

通过设置图像视图的

.image

属性，您无法从一个UIImage“交叉淡入”到另一个UIImage

不过，您可以使用“中间”图像视图来执行此操作

假设您有一个通过

IBOutlet

连接的

UIImageView

，以及一个通过iAction连接的按钮：

//
//  CrossFadeViewController.m
//
//  Created by Don Mag on 3/7/18.
//

#import "CrossFadeViewController.h"

@interface CrossFadeViewController ()

@property (strong, nonatomic) IBOutlet UIImageView *imgMirror;

@end

@implementation CrossFadeViewController

- (IBAction)didTap:(id)sender {

    [self crossFadeTo:@"NewImage"];

}

- (void) crossFadeTo:(NSString *)newImageName {

    UIImageView *toImageView;

    // create a new UIImageView with the new Image
    toImageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:newImageName]];

    // set the new image view's frame to match the existing one
    toImageView.frame = _imgMirror.frame;

    // cross-fade / dissolve from the existing image view to the new one
    [UIView transitionFromView:_imgMirror
                        toView:toImageView
                      duration:0.33
                       options:UIViewAnimationOptionTransitionCrossDissolve
                    completion:^(BOOL finished) {
                        // when animation is finished
                        // remove the "old" image view from its superview
                        [_imgMirror removeFromSuperview];
                        // assign the new image view to the IBOutlet property
                        _imgMirror = toImageView;
                    }];

}

@end

通过设置图像视图的

.image

属性，您无法从一个UIImage“交叉淡入”到另一个UIImage

不过，您可以使用“中间”图像视图来执行此操作

假设您有一个通过

IBOutlet

连接的

UIImageView

，以及一个通过iAction连接的按钮：

//
//  CrossFadeViewController.m
//
//  Created by Don Mag on 3/7/18.
//

#import "CrossFadeViewController.h"

@interface CrossFadeViewController ()

@property (strong, nonatomic) IBOutlet UIImageView *imgMirror;

@end

@implementation CrossFadeViewController

- (IBAction)didTap:(id)sender {

    [self crossFadeTo:@"NewImage"];

}

- (void) crossFadeTo:(NSString *)newImageName {

    UIImageView *toImageView;

    // create a new UIImageView with the new Image
    toImageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:newImageName]];

    // set the new image view's frame to match the existing one
    toImageView.frame = _imgMirror.frame;

    // cross-fade / dissolve from the existing image view to the new one
    [UIView transitionFromView:_imgMirror
                        toView:toImageView
                      duration:0.33
                       options:UIViewAnimationOptionTransitionCrossDissolve
                    completion:^(BOOL finished) {
                        // when animation is finished
                        // remove the "old" image view from its superview
                        [_imgMirror removeFromSuperview];
                        // assign the new image view to the IBOutlet property
                        _imgMirror = toImageView;
                    }];

}

@end

//
//  CrossFadeViewController.m
//
//  Created by Don Mag on 3/7/18.
//

#import "CrossFadeViewController.h"

@interface CrossFadeViewController ()

@property (strong, nonatomic) IBOutlet UIImageView *imgMirror;

@end

@implementation CrossFadeViewController

- (IBAction)didTap:(id)sender {

    [self crossFadeTo:@"NewImage"];

}

- (void) crossFadeTo:(NSString *)newImageName {

    UIImageView *toImageView;

    // create a new UIImageView with the new Image
    toImageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:newImageName]];

    // set the new image view's frame to match the existing one
    toImageView.frame = _imgMirror.frame;

    // cross-fade / dissolve from the existing image view to the new one
    [UIView transitionFromView:_imgMirror
                        toView:toImageView
                      duration:0.33
                       options:UIViewAnimationOptionTransitionCrossDissolve
                    completion:^(BOOL finished) {
                        // when animation is finished
                        // remove the "old" image view from its superview
                        [_imgMirror removeFromSuperview];
                        // assign the new image view to the IBOutlet property
                        _imgMirror = toImageView;
                    }];

}

@end