相关疑难解决方法(0)

我有一个实例,MKMapView并希望使用自定义注释图标,而不是MKPinAnnotationView提供的标准图钉图标.所以,我已经设置了一个名为CustomMapAnnotation的MKAnnotationView的子类,并且重写-(void)drawRect:了绘制CGImage.这有效.

当我尝试复制.animatesDropMKPinAnnotationView提供的功能时出现问题; 当注释被添加到MKMapView实例时,我希望我的图标能够逐渐显示,从上到下以及从左到右顺序显示.

这是 - (void)drawRect:用于CustomMapAnnotation,当你只绘制UIImage(这是第二行所做的)时它可以工作:

- (void)drawRect:(CGRect)rect {
 [super drawRect:rect];
 [((Incident *)self.annotation).smallIcon drawInRect:rect];
 if (newAnnotation) {
  [self animateDrop];
  newAnnotation = NO;
 }
} 

添加animateDrop方法时出现问题:

-(void)animateDrop {
 CGContextRef myContext = UIGraphicsGetCurrentContext();

 CGPoint finalPos = self.center;
 CGPoint startPos = CGPointMake(self.center.x, self.center.y-480.0);
 self.layer.position = startPos;

 CABasicAnimation *theAnimation;
 theAnimation=[CABasicAnimation animationWithKeyPath:@"position"];
 theAnimation.fromValue=[NSValue valueWithCGPoint:startPos];
 theAnimation.toValue=[NSValue valueWithCGPoint:finalPos];
 theAnimation.removedOnCompletion = NO;
 theAnimation.fillMode = kCAFillModeForwards;
 theAnimation.delegate = self;
 theAnimation.beginTime = 5.0 * (self.center.x/320.0);
 theAnimation.duration = 1.0;
 [self.layer addAnimation:theAnimation …