Xcode 如何上下移动图像动画 [英] Xcode How to move an image up and down animation

问题描述

嘿，我试图将图像视图向下移动到屏幕中间，然后再回到顶部.这是我的代码，现在它只是移动到中间并停留在那里.

Hey im trying to move an imageview down to the middle of the screen then back up to the top . here is my code , right now it just moves to the middle and stays there .

-(void)lineGoBack
{
    //move diagonally down
    line.center = CGPointMake(line.center.x,
                              line.center.y-10);
    //start time for first method
    [NSTimer scheduledTimerWithTimeInterval:.5 target:self selector:@selector(LineMovement) userInfo:nil repeats:NO];
}


//The LINE
-(void)LineMovement
{ 
    lineMovementOffset = CGPointMake(line.center.x, screenSizeY/2);

    //move diagonally up
    line.center = CGPointMake(line.center.x,
                              line.center.y+10);

    //start time for second method
    [NSTimer scheduledTimerWithTimeInterval:.5 target:self selector:@selector(lineGoBack) userInfo:nil repeats:NO];
}

推荐答案

我不喜欢将基于块的动画用于链式动画 - 它们往往变得难以阅读.我建议使用 关键帧动画.这也使您能够轻松地为动画定义许多中间点，或为动画添加更多高级功能，例如曲线.

I don't like using blocks based animations for chained animations - they tend to grow difficult to read. I would suggest using keyframe animations. This also enables you to easily define a number of intermediary points to your animation, or add more advanced features to your animation, e.g. curves.

这里有一个示例，说明如何在三个点之间线性地为 UIView 设置动画.

Here is an example of how you can animate a UIView linearly between three points.

CGPoint startPoint = (CGPoint){100.f, 100.f};
CGPoint middlePoint = (CGPoint){400.f, 400.f};
CGPoint endPoint = (CGPoint){600.f, 100.f};

CGMutablePathRef thePath = CGPathCreateMutable();
CGPathMoveToPoint(thePath, NULL, startPoint.x, startPoint.y);
CGPathAddLineToPoint(thePath, NULL, middlePoint.x, middlePoint.y);
CGPathAddLineToPoint(thePath, NULL, endPoint.x, endPoint.y);

CAKeyframeAnimation *animation = [CAKeyframeAnimation animationWithKeyPath:@"position"];
animation.duration = 3.f;
animation.path = thePath;
[self.animatedView.layer addAnimation:animation forKey:@"position"];
self.animatedView.layer.position = endPoint;

要在两点之间制作无限动画，您可以使用以下代码.将它应用到 UIImageView 会起到同样的作用.

To do an infinite animation between two points, you could use the code below. Applying it to a UIImageView would work the same.

CGPoint startPoint = (CGPoint){100.f, 100.f};
CGPoint endPoint = (CGPoint){400.f, 400.f};

CGMutablePathRef thePath = CGPathCreateMutable();
CGPathMoveToPoint(thePath, NULL, startPoint.x, startPoint.y);
CGPathAddLineToPoint(thePath, NULL, endPoint.x, endPoint.y);

CAKeyframeAnimation *animation = [CAKeyframeAnimation animationWithKeyPath:@"position"];
animation.duration = 3.f;
animation.path = thePath;
animation.autoreverses = YES;
animation.repeatCount = INFINITY;
[self.animatedView.layer addAnimation:animation forKey:@"position"];

这篇关于Xcode 如何上下移动图像动画的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！