问如何在MKTileOverLay中使用iOS7？

EN

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.



    NSString *template = @"http://c.tile.openstreetmap.org/{z}/{x}/{y}.png";
    MKTileOverlay *overLay = [[MKTileOverlay alloc] initWithURLTemplate:template];
    overLay.canReplaceMapContent = YES;
    [self.mapView addOverlay:overLay level:MKOverlayLevelAboveLabels];
    [self.mapView setRegion:MKCoordinateRegionMake(CLLocationCoordinate2DMake(37.776884, -122.387255), MKCoordinateSpanMake(0.25, 0.25))];

}

-(MKTileOverlayRenderer *)mapView:(MKMapView*)mapView rendererForOverlay:(id<MKOverlay>)overlay {

    MKTileOverlayRenderer *renderer = [[MKTileOverlayRenderer alloc] initWithOverlay:overlay];
    renderer.alpha = 0.6;
    return renderer;