Sept 26th 2012 update :for erasing iOS6 base maps look here: https://blog.sumbera.com/2012/09/26/how-to-erase-ios6-maps-in-mapkit/
I have searched this and couldn’t find any answer, so here is my own research so far on this subject. You can disable MapKit base layers using 3 approaches:
#1 remove subview from MKMapView (quite bad as you will loose all overlays too)
#2 use undocumented function (bad too as this will be rejected by Apple approval process):
// get MKMapTileView from view hierarchy
UIView * mkMapTileView = [((UIView*) [ ((UIView*)[self.subviews objectAtIndex:0]).
subviews objectAtIndex:0]).subviews objectAtIndex:0];
// call undocumented method
if ( [mkMapTileView respondsToSelector:@selector(setDrawingEnabled:)]){
[mkMapTileView performSelector:@selector(setDrawingEnabled:) withObject:(id) NO];
#3 use method swizzle
inspired by http://www.mikeash.com/pyblog/friday-qa-2010-01-29-method-replacement-for-fun-and-profit.html
http://atastypixel.com/blog/making-uitoolbar-and-uinavigationbars-background-totally-transparent/
this method is fine as it is official method and enables you to ‘subclass’ a class that you don’t have access in compile time.
#import <objc/runtime.h>
// original method declaration
static void (*_origDrawLayerInContext)(id, SEL, CALayer*, CGContextRef);
// set up subclass in runtime..in some entering method
UIView * mkMapTileView = [((UIView*) [ ((UIView*)[self.subviews objectAtIndex:0]). subviews objectAtIndex:0]).subviews objectAtIndex:0];
Method origMethod = class_getInstanceMethod([mkMapTileView class], @selector(drawLayer:inContext:));
_origDrawLayerInContext = (void *)method_getImplementation(origMethod);
if(!class_addMethod([mkMapTileView class], @selector(drawLayer:inContext:), (IMP)OverrideDrawLayerInContext, method_getTypeEncoding(origMethod)))
method_setImplementation(origMethod, (IMP)OverrideDrawLayerInContext);
// implement our Override
static void OverrideDrawLayerInContext(UIView *self, SEL _cmd, CALayer *layer, CGContextRef context) {
// possibly call original method if you leave it empty base google maps will not be displayed. You can draw custom content here as well...
// _origDrawLayerInContext(self, _cmd, layer, context);
}
Both the stride (bytes of padding added to each row), as well as the extended rows (rows of padding at the bottom or top of the buffer) are important. The extended rows are what changed in iOS6; you can find out how many rows of padding are added to the buffer using: CVPixelBufferGetExtendedPixels(pixelBuffer, &columnsLeft, &columnsRight, &rowsTop, &rowsBottom)
∫ ∪ ∧∴ ∋ ∈ ⊇ ∧ 