IOS图片转base64字符串和字符串转回图片

    UIImage *_originImage = [UIImage imageNamed:@"full_playlist_hl.png"];

    NSData *_data = UIImageJPEGRepresentation(_image, 1.0f);

    NSString *_encodedImageStr = [_data base64Encoding];

    NSLog(@"===Encoded image:\n%@", _encodedImageStr);

Base64字符串转UIImage图片：

    NSData *_decodedImageData   = [[NSData alloc] initWithBase64Encoding:_encodedImageStr];

    UIImage *_decodedImage      = [UIImage imageWithData:_decodedImageData];

    NSLog(@"===Decoded image size: %@", NSStringFromCGSize(_decodedImage.size));