Base64图片 -> UIImage

- (UIImage *) dataURL2Image: (NSString *) imgSrc  
{  
    NSURL *url = [NSURL URLWithString: imgSrc];  
    NSData *data = [NSData dataWithContentsOfURL: url];  
    UIImage *image = [UIImage imageWithData: data];  

    return image;  
}  

UIImage -> Base64图片

- (BOOL) imageHasAlpha: (UIImage *) image  
{  
    CGImageAlphaInfo alpha = CGImageGetAlphaInfo(image.CGImage);  
    return (alpha == kCGImageAlphaFirst ||  
            alpha == kCGImageAlphaLast ||  
            alpha == kCGImageAlphaPremultipliedFirst ||  
            alpha == kCGImageAlphaPremultipliedLast);  
}  
- (NSString *) image2DataURL: (UIImage *) image  
{  
    NSData *imageData = nil;  
    NSString *mimeType = nil;  

    if ([self imageHasAlpha: image]) {  
        imageData = UIImagePNGRepresentation(image);  
        mimeType = @"image/png";  
    } else {  
        imageData = UIImageJPEGRepresentation(image, 1.0f);  
        mimeType = @"image/jpeg";  
    }  

    return [NSString stringWithFormat:@"data:%@;base64,%@", mimeType,  
           [imageData base64EncodedStringWithOptions: 0]];  

}