如何在ios中製作圓形動畫

Question

如果我單擊「鍛鍊」按鈕，我想要顯示紅色圓形動畫並圍繞圖像。我想移動Storyboard中的另一個班級。我怎樣才能做到這一點？

Answer 1

使用UIBezierPath或CAShapeLayer，就可以實現這一點。我測試了下面的代碼在我的項目之一，並發現它的工作：

- (void)viewDidLoad 
{ 
    [super viewDidLoad]; 

    int radius = 50; 
    CAShapeLayer *circle = [CAShapeLayer layer]; 
    // Make a circular shape 
    circle.path = [UIBezierPath bezierPathWithRoundedRect:CGRectMake(0, 0, 2.0*radius, 2.0*radius) 
              cornerRadius:radius].CGPath; 
    // Center the shape in self.view 
    circle.position = CGPointMake(CGRectGetMidX(self.view.frame)-radius, 
            CGRectGetMidY(self.view.frame)-radius); 

    // Configure the apperence of the circle 
    circle.fillColor = [UIColor clearColor].CGColor; 
    circle.strokeColor = [UIColor redColor].CGColor; 
    circle.lineWidth = 5; 

    // Add to parent layer 
    [self.view.layer addSublayer:circle]; 

    // Configure animation 
    CABasicAnimation *drawAnimation = [CABasicAnimation animationWithKeyPath:@"strokeEnd"]; 
    drawAnimation.duration   = 5.0; 
    drawAnimation.repeatCount   = 1.0; // Animate only once.. 

    // Animate from no part of the stroke being drawn to the entire stroke being drawn 
    drawAnimation.fromValue = [NSNumber numberWithFloat:0.0f]; 
    drawAnimation.toValue = [NSNumber numberWithFloat:1.0f]; 

    // Experiment with timing to get the appearence to look the way you want 
    drawAnimation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseIn]; 

    // Add the animation to the circle 
    [circle addAnimation:drawAnimation forKey:@"draw"]; 
    // Do any additional setup after loading the view, typically from a nib. 
} 

輸出如下：在按鈕的clickevent