警告：</p> <p>不兼容的指針類型返回「MKCircleRenderer *」：在更新代碼

Question

我試圖擺脫一些depricated代碼在MapView創建覆蓋，現在我facingh此警告兼容的指針類型從結果類型'MKOverlayView * _Nonnull'

我讀過很多關於這個問題的Q &，但直到現在我還是無法弄清楚。我的代碼有什麼問題？

// 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

錯誤說circleView是MKCircleRenderer *類型，但是你的返回類型爲MKOverlayView *。這些類型應該是相同的。

- (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; 
}