UIImage+ImmediateLoad.m

@interface UIImage(ImmediateLoad)

+ (UIImage*)imageImmediateLoadWithContentsOfFile:(NSString*)path;

@end

@implementation UIImage(ImmediateLoad)

+ (UIImage*)imageImmediateLoadWithContentsOfFile:(NSString*)path {
    UIImage *image = [[UIImage alloc] initWithContentsOfFile:path];
    CGImageRef imageRef = [image CGImage];
    CGRect rect = CGRectMake(0.f, 0.f, CGImageGetWidth(imageRef), CGImageGetHeight(imageRef));
    CGContextRef bitmapContext = CGBitmapContextCreate(NULL,
                                                       rect.size.width,
                                                       rect.size.height,
                                                       CGImageGetBitsPerComponent(imageRef),
                                                       CGImageGetBytesPerRow(imageRef),
                                                       CGImageGetColorSpace(imageRef),
                                                       CGImageGetBitmapInfo(imageRef)
                                                       );
    CGContextDrawImage(bitmapContext, rect, imageRef);
    CGImageRef decompressedImageRef = CGBitmapContextCreateImage(bitmapContext);
    UIImage *decompressedImage = [UIImage imageWithCGImage:decompressedImageRef];
    CGImageRelease(decompressedImageRef);
    CGContextRelease(bitmapContext);
    [image release];
    return decompressedImage;
}

@end

Hi Steve, I'm pretty sure that the imageRef will also have an internal pointer to the decompressed bits. You could just create a new context with the UIKit functions, draw image then discard the context. The UIImage image would then have an indirect pointer to the decompressed image.

The snippet works on my iphone, but then in the simulator it doesn't work. I get something like : CGBitmapContextCreate: unsupported parameter combination: 8 integer bits/component; 24 bits/pixel; 3-component color space; kCGImageAlphaNone; 1440 bytes/row.

I noticed that for the same troubled image, on the device CGImageGetBytesPerRow(imageRef) == 1920 and width*4 == 1920, but in the simulator CGImageGetBytesPerRow(imageRef) == 1440.

I then tried what steipete suggested and it works on both the device and simulator. Thoughts?