警告：</p> <p>不兼容的指针类型返回“MKCircleRenderer *”：在更新代码

Question

我试图摆脱一些depricated代码在MapView创建覆盖，现在我facingh此警告兼容的指针类型从结果类型'MKOverlayView * _Nonnull'

我读过很多关于这个问题的Q &，但直到现在我还是无法弄清楚。我的代码有什么问题？

// Create overlay 
- (MKOverlayView *)mapView:(MKMapView *)mapView viewForOverlay:(id<MKOverlay>)overlay{ 

MKCircleRenderer *circleView = [[MKCircleRenderer alloc] initWithOverlay:overlay]; 
circleView.fillColor = [[UIColor cyanColor]colorWithAlphaComponent:0.5]; 
circleView.strokeColor = [[UIColor blueColor]colorWithAlphaComponent:0.8]; 
circleView.lineWidth = 1; 
return circleView; 
} 

Answer 1

错误说circleView是MKCircleRenderer *类型，但是你的返回类型为MKOverlayView *。这些类型应该是相同的。

- (MKCircleRenderer *)mapView:(MKMapView *)mapView viewForOverlay:(id<MKOverlay>)overlay{ 

MKCircleRenderer *circleView = [[MKCircleRenderer alloc] initWithOverlay:overlay]; 
circleView.fillColor = [[UIColor cyanColor]colorWithAlphaComponent:0.5]; 
circleView.strokeColor = [[UIColor blueColor]colorWithAlphaComponent:0.8]; 
circleView.lineWidth = 1; 
return circleView; 
}