UIWebView底部的黑色随着动画而增加？

Question

有一些帖子，UIWebView底部是黑色的，可以通过两种简单的方式解决。

1. Clear Background of UIWebView
2. Set Opaque to NO.

但是，这只解决了静态 UIWebView 的问题，它不会改变其 Frame 或 Constraints。

就我而言，我有一个 UIWebView，它非常简单地拖放到 Storyboard 的 ViewController 的 View 上。无继承。我将背景设置为清除并将不透明设置为 NO。

到目前为止看起来还不错。但是当我应用动画时，使用 Facebook POP 库

1. SetOpaque = YES, With Animation is clips the UIWebView's content showing black color.



2. SetOpaque = NO, With Animation is clips the UIWebView's content showing nothing (a View or something comes in front)



-(void) setConstraint {

    _topConstraintValue = self.topConstraint.constant - 200;

    NSLog(@"Value is UP %f " ,_topConstraintValue);

}

- (IBAction)animateUp:(UIButton *)sender {

    [self setConstraint];

    [VSAnimation popChangeConstraintForBasicAnimation:self.topConstraint begin:0.5 newConstant:_topConstraintValue   withDuartion:0.5 isEaseInAnimation:NO withCompletionBlock:nil];

}




-(void) setConstraintDown {

    _topConstraintValue = 0;
    _topConstraintValue = self.topConstraint.constant;

    NSLog(@"Value is Down %f " ,_topConstraintValue);

}


- (IBAction)animateDown:(UIButton *)sender {

    [self setConstraintDown];

    [VSAnimation popChangeConstraintForBasicAnimation:self.topConstraint begin:0.5 newConstant:[self getAnimatableConstraint:_topConstraintValue] withDuartion:0.5 isEaseInAnimation:NO withCompletionBlock:nil];
}


-(float)getAnimatableConstraint:(float)constant{

    return  constant+200.0;
}

-(float)getReverseAnimatableConstraint:(float)constant{

    return  constant-200.0;
}

其中，VS里面的方法如下

//VSAnimation.m

+(void)popChangeConstraintForBasicAnimation:(NSLayoutConstraint *) layoutConstraintToPopChange begin:(float) beginTime newConstant:(CGFloat) newConstant withDuartion:(float)duration isEaseInAnimation:(BOOL)isEaseIn withCompletionBlock:(void (^)(POPAnimation *anim, BOOL finished)) completitionBlock{

    NSString *key = [NSString stringWithFormat:@"constraints_changed_%@", layoutConstraintToPopChange];

    POPBasicAnimation *basicAnim = [layoutConstraintToPopChange pop_animationForKey:key];
    if(basicAnim){
        basicAnim.toValue = @(newConstant);
        basicAnim.completionBlock = completitionBlock;
    }else{

        basicAnim = [POPBasicAnimation animationWithPropertyNamed:kPOPLayoutConstraintConstant];
        if(isEaseIn)
            basicAnim.timingFunction=[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseIn];
        else
            basicAnim.timingFunction=[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseOut];
        basicAnim.toValue = @(newConstant);
        basicAnim.completionBlock = completitionBlock;
        basicAnim.beginTime = [self timeWithDelay:beginTime];
        basicAnim.delegate = self;
        basicAnim.duration = duration;

        [layoutConstraintToPopChange pop_addAnimation:basicAnim forKey:key];
    }
}

底部的这条黑线/透明线是什么。 当为 UIWebView 设置动画时，如何阻止这种情况增加。

图片：

显示动画向上和动画向下。

Answer 1

@VS，看了你的源码后，我看到第二个 webview 的约束似乎设置错误。在我删除高度约束WV2.height = 0.095 * height 后，问题就消失了。您必须正确设置 WV2 的高度约束。