图片Base64

调用方法

NSString *str  = [self image2DataURL:[UIImage imageNamed:@"guanbi.png"]];

实现方法

- (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]];
    
}