You can use CGContextScaleCTM on a 2D quartz wireframe to smoothly scale high resolution images.

You can find the Apple example app listed below. MoveMe_APLMoveMeView_m

TiledImageView.h

#import <UIKit/UIKit.h>

@interface TiledImageView : UIView {
    CGFloat imageScale;
    UIImage* image;
    CGRect imageRect;
}
@property (retain) UIImage* image;

-(id)initWithFrame:(CGRect)_frame image:(UIImage*)_image scale:(CGFloat)_scale;

@end

      

        
        
        
      

    

TiledImageView.m

#import "TiledImageView.h"
#import <QuartzCore/QuartzCore.h>

@implementation TiledImageView

@synthesize image;

// Set the layer class to be CATiledLayer.
+ (Class)layerClass {
    Return [CATiledLayer class];
}

- (void)dealloc {
    [image release];
    //--
    [super dealloc];
}

// Create a new TiledImageView with the desired frame and scale.
-(id)initWithFrame:(CGRect)_frame image:(UIImage*)_image scale:(CGFloat)_scale {
    if ((self = [super initWithFrame:_frame])) {
        self.image = _image;
        imageRect = CGRectMake(0.0f, 0.0f, CGImageGetWidth(image.CGImage), CGImageGetHeight(image.CGImage));
        imageScale = _scale;
        CATiledLayer *tiledLayer = (CATiledLayer *)[self layer];
        // levelsOfDetail and levelsOfDetailBias determine how
        // the layer is rendered at different zoom levels.  This
        // only matters while the view is zooming, since once the 
        // the view is done zooming a new TiledImageView is created
        // at the correct size and scale.
        tiledLayer.levelsOfDetail = 4;
        tiledLayer.levelsOfDetailBias = 4;
        tiledLayer.tileSize = CGSizeMake(512.0, 512.0); 
    }
    return self;
}

-(void)drawRect:(CGRect)_rect {
    CGContextRef context = UIGraphicsGetCurrentContext();    
    CGContextSaveGState(context);
    // Scale the context so that the image is rendered 
    // at the correct size for the zoom level.
    CGContextScaleCTM(context, imageScale,imageScale);  
    CGContextDrawImage(context, imageRect, image.CGImage);
    CGContextRestoreGState(context);    
}
@end