iOS：在地圖上放大和縮小效果

Question

我已創建地圖，如this link所示，並且其工作完美。

但問題是，它只能放大一種方式（它只會變大）。我怎麼能使它在任何方面工作？

可能就像我們在google map（加號 - 減號棒在左側）。

Answer 1

對於ZoomIn

-(void)zoomIn 
{ 
    region.span.latitudeDelta = region.span.latitudeDelta/4 ; 
    region.span.longitudeDelta = region.span.longitudeDelta/4; 



    region.center.latitude = mapView.centerCoordinate.latitude ; 
    region.center.longitude = mapView.centerCoordinate.longitude ; 
    [mapView setRegion:region animated:YES]; 
} 

對於縮小（ZoomOut）

-(void)zoomOut 
{ 
    region.span.latitudeDelta = region.span.latitudeDelta*4 ; 
    region.span.longitudeDelta = region.span.longitudeDelta*4; 



    region.center.latitude = mapView.centerCoordinate.latitude ; 
    region.center.longitude = mapView.centerCoordinate.longitude ; 
    [mapView setRegion:region animated:YES]; 
} 

可以使用在該結構中的δ值，以指示地圖的期望 縮放水平，與對應於更小的增量值一個 更高的縮放級別。

欲瞭解更多信息，請參閱此link。

Answer 2

這是Midhun VP和Slavco Petkovski的回答修訂版本，它在設置latitudeDelta過大時避免了zoomOut中「無效區域」的NSInvalidArgumentException。放大似乎沒有任何問題 - 一旦達到極限，它不會再放大。

- (void)zoomIn { 
    MKCoordinateRegion region = [self.mapView region]; 
    region.span.latitudeDelta = region.span.latitudeDelta/4; 
    region.span.longitudeDelta = region.span.longitudeDelta/4; 
    region.center.latitude = self.mapView.centerCoordinate.latitude; 
    region.center.longitude = self.mapView.centerCoordinate.longitude; 
    [self.mapView setRegion:region animated:YES]; 
    //NSLog(@"zoomIn: center %lf, %lf; spanDelta %lf, %lf, upper left %lf, %lf; lower right %lf %lf", region.center.latitude, region.center.longitude, region.span.latitudeDelta, region.span.longitudeDelta, region.center.latitude + region.span.latitudeDelta/2, region.center.longitude - region.span.longitudeDelta/2, region.center.latitude - region.span.latitudeDelta/2, region.center.longitude + region.span.longitudeDelta/2); 
} 

- (void)zoomOut { 
    MKCoordinateRegion region = [self.mapView region]; 
    region.span.latitudeDelta = region.span.latitudeDelta*4; 
    region.span.longitudeDelta = region.span.longitudeDelta*4; 
    region.center.latitude = self.mapView.centerCoordinate.latitude; 
    region.center.longitude = self.mapView.centerCoordinate.longitude; 

    // The region upper latitude must not exceed 90.0 degrees, and the region lower latitude must not fall below -90.0. 
    double upperLatitude = region.center.latitude + region.span.latitudeDelta/2.0; 
    double lowerLatitude = region.center.latitude - region.span.latitudeDelta/2.0; 
    if (upperLatitude > 90 || lowerLatitude < -90) { 
     region.center.latitude = 0.0; 
     double spanRatio = region.span.latitudeDelta/region.span.longitudeDelta; 
     region.span.latitudeDelta = 180; 
     region.span.longitudeDelta = 180/spanRatio; 
    } 
    [self.mapView setRegion:region animated:YES]; 
    //NSLog(@"zoomOut: center %lf, %lf; spanDelta %lf, %lf, upper left %lf, %lf; lower right %lf %lf", region.center.latitude, region.center.longitude, region.span.latitudeDelta, region.span.longitudeDelta, region.center.latitude + region.span.latitudeDelta/2, region.center.longitude - region.span.longitudeDelta/2, region.center.latitude - region.span.latitudeDelta/2, region.center.longitude + region.span.longitudeDelta/2); 
}