Question

在3.1中,我一直在使用“快车”MapView制作地图图象,在向用户介绍这些图像之前,我可以轮流、作物等等。在3.2和4.0中,这种技术不再奏效。这里有一些说明问题的法典,随后是我的理论。

     // create map view

     _mapView = [[MKMapView alloc] initWithFrame:CGRectMake(0, 0, MAP_FRAME_SIZE, MAP_FRAME_SIZE)];
     _mapView.zoomEnabled = NO;   
     _mapView.scrollEnabled = NO;
     _mapView.delegate = self;    
     _mapView.mapType = MKMapTypeSatellite;

     // zoom in to something enough to fill the screen
     MKCoordinateRegion region;    
     CLLocationCoordinate2D center = {30.267222, -97.763889};

     region.center = center;    
     MKCoordinateSpan span = {0.1, 0.1 };    
     region.span = span;    
     _mapView.region = region;

     // set scrollview content size to full the imageView  
     _scrollView.contentSize = _imageView.frame.size;

     // force it to load

#ifndef __IPHONE_3_2

     // in 3.1 we can render to an offscreen context to force a load    
     UIGraphicsBeginImageContext(_mapView.frame.size);    
     [_mapView.layer renderInContext:UIGraphicsGetCurrentContext()];
     UIGraphicsEndImageContext();

#else

     // in 3.2 and above, the renderInContext trick doesn t work...    
     // this at least causes the map to render, but it s clipped to what appears to be    
     // the viewPort size, plus some padding    
     [self.view addSubview:_mapView];          

#endif

当该地图装满时,我 s弄该地图,在我的滚动概览中加以uff击。

- (void)mapViewDidFinishLoadingMap:(MKMapView *)mapView {    
     NSLog(@"[MapBuilder] mapViewDidFinishLoadingMap");

     // render the map to a UIImage
     UIGraphicsBeginImageContext(mapView.bounds.size);

     // the first sub layer is just the map, the second is the google layer, this sublayer structure might change of course

     [[[mapView.layer sublayers] objectAtIndex:0] renderInContext:UIGraphicsGetCurrentContext()];

     // we are done with the mapView at this point, we need its ram!    
     _mapView.delegate = nil;     

     [_mapView release];
     [_mapView removeFromSuperview];    
     _mapView = nil;

     UIImage* mapImage = [UIGraphicsGetImageFromCurrentImageContext() retain];
     UIGraphicsEndImageContext();     

     _imageView.image = mapImage;
     [mapImage release], mapImage = nil;  
}

第一个问题是,在3.1中,使情况趋于一致将触发地图开始装载。这在3.2、4.0中不再奏效。我发现的唯一事情是暂时增加这一看法的地图(即使之可见)。问题是,地图只给屏幕的可见区域加一点dding。框架/限值是罚款,但似乎“有益”优化了装货,以限制在屏幕上或靠近屏幕上看到的碎片。

如何迫使地图满负荷的想法? 是否有其他问题?

友情链接