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  • iOS 对象沿着指定路径进行动画

    以下方法可作为两步实现:
        以下方法在自定义view的类里面实现,可放在自定义函数中自行控制触法。也可放在drawRect或layoutSubviews里面让view在显 示时触法。但推荐放在自定义view中触发,因为这样才可以做到自行控制,并保证同时只有一个在运行,否则会因为view的改变导致重绘,导致同时执行多 个相同的动画,会影响效果和耗费内存。

        一》让view对象沿指定的路径进行动画的方法:

      以下是指定路径:
        CAKeyframeAnimation *pathAnimation = [CAKeyframeAnimation animationWithKeyPath:@"position"];
        //Set some variables on the animation
        pathAnimation.calculationMode = kCAAnimationPaced;
        //We want the animation to persist - not so important in this case - but kept for clarity
        //If we animated something from left to right - and we wanted it to stay in the new position,
        //then we would need these parameters
        pathAnimation.fillMode = kCAFillModeForwards;
        pathAnimation.removedOnCompletion = NO;
        pathAnimation.duration = 10;
        //Lets loop continuously for the demonstration
        pathAnimation.repeatCount = 10;

      //Setup the path for the animation - this is very similar as the code the draw the line
        //instead of drawing to the graphics context, instead we draw lines on a CGPathRef
        //CGPoint endPoint = CGPointMake(310, 450);
        CGMutablePathRef curvedPath = CGPathCreateMutable();
        CGPathMoveToPoint(curvedPath, NULL, 10, 10);
        CGPathAddQuadCurveToPoint(curvedPath, NULL, 10, 450, 310, 450);
        CGPathAddQuadCurveToPoint(curvedPath, NULL, 310, 10, 10, 10);

      //Now we have the path, we tell the animation we want to use this path - then we release the path
        pathAnimation.path = curvedPath;
        CGPathRelease(curvedPath);

        在指定路径后,指定动画的对象,(在此用UIImageView举例:)
        UIImageView *circleView = [[UIImageView alloc] initWithImage:circle];
        circleView.frame = CGRectMake(1, 1, 40, 40);
        [self addSubview:circleView];

        //Add the animation to the circleView - once you add the animation to the layer, the animation starts
        [circleView.layer addAnimation:pathAnimation
        forKey:@"moveTheSquare"];

        二>.若要把指定的路径以线条或其他方法显示出来,则要绘制路径,方法是:

      UIGraphicsBeginImageContext(CGSizeMake(320,460));
        CGContextRef ctx = UIGraphicsGetCurrentContext();

    //Set variables in the context for drawing
        CGContextSetLineWidth(ctx, 1.5);
        CGContextSetStrokeColorWithColor(ctx, [UIColor whiteColor].CGColor);

    //Set the start point of your drawing
        CGContextMoveToPoint(ctx, 10, 10);
        //The end point of the line is 310,450 .... i'm also setting a reference point of 10,450
        //A quadratic bezier curve is drawn using these coordinates - experiment and see the results.
        CGContextAddQuadCurveToPoint(ctx, 10, 450, 310, 450);
        //Add another curve, the opposite of the above - finishing back where we started
        CGContextAddQuadCurveToPoint(ctx, 310, 10, 10, 10);

    //Draw the line
        CGContextDrawPath(ctx, kCGPathStroke);

        若要绘制图片背景(直接添加即可),则:
        //With the image, we need a UIImageView
        UIImage *image = [UIImage imagewithName:@"a.png"];
        UIImageView *curveView = [[UIImageView alloc] image];
        //Set the frame of the view - which is used to position it when we add it to our current UIView
        curveView.frame = CGRectMake(1, 1, 320, 460);
        curveView.backgroundColor = [UIColor greenColor];
        [self addSubview:curveView];

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  • 原文地址:https://www.cnblogs.com/zhouwenwen/p/4490542.html
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