// 畫弧線- (void)drawHalfCircle {  loadingLayer = [self drawCircle];     // 這個是用于指定畫筆的開始與結束點  loadingLayer.strokeStart = 0.0;  loadingLayer.strokeEnd = 0.75;} - (CAShapeLayer *)drawCircle {  CGRect frame = CGRectMake(0, 0, self.frame.size.height, self.frame.size.height);  CAShapeLayer *circleLayer = [CAShapeLayer layer];  // 指定frame，只是為了設置寬度和高度  circleLayer.frame = frame;  // 設置居中顯示  circleLayer.position = CGPointMake(self.frame.size.height/2, self.frame.size.height/2);  // 設置填充顏色  circleLayer.fillColor = [UIColor clearColor].CGColor;  // 設置線寬  circleLayer.lineWidth = 1;  // 設置線的顏色  circleLayer.strokeColor = kSelfborderColor.CGColor;  // 使用UIBezierPath創(chuàng)建路徑  UIBezierPath *circlePath = [UIBezierPath bezierPathWithOvalInRect:frame];  // 設置CAShapeLayer與UIBezierPath關聯  circleLayer.path = circlePath.CGPath;  // 將CAShaperLayer放到某個層上顯示  [self.layer addSublayer:circleLayer];  return circleLayer;}