无法使用 NSData（包含 png）初始化 NSMutableData

Question

我的 iPhone 应用程序出现错误。我使用 CameraPicker 制作并获取图片，然后将其提供给我的方法 sendPhoto，该方法会将照片发送到 TweetPhoto。在我用 NSData 初始化 NSMutableDate 之前，一切都很好。代码如下：

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info {
    [picker dismissModalViewControllerAnimated:YES];
    NSData *imageData = [info objectForKey:@"UIImagePickerControllerOriginalImage"];
    [self sendPhoto:(NSString*)@"lola" tweet:(BOOL)TRUE photo:(NSData*)imageData tags:(NSString*)@"" longitude:(float)1024 latitude:(float)512];
}

这里是 sendPhoto 方法：

- (void)sendPhoto:(NSString*)message tweet:(BOOL)tweet photo:(NSData*)photo tags:(NSString*)tags longitude:(float)longitude latitude:(float)latitude {
    NSString *url;
    if (tweet) {
        url = [NSString stringWithFormat:@"http://www.tweetphoto.com/uploadandpostapiwithkey.php"];
    } else {
        url = [NSString stringWithFormat:@"http://www.tweetphoto.com/uploadapiwithkey.php"];
    }

    NSString * boundary = @"tweetPhotoBoundaryParm";
    NSMutableData *postData = [NSMutableData dataWithCapacity:[photo length] + 1024];
    //!!!Here is the error!!!!                      
    NSUserDefaults *prefs = [NSUserDefaults standardUserDefaults];

    NSString * userNameString = [NSString stringWithFormat:@"Content-Disposition: form-data; name=\"username\"\r\n\r\n%@", [prefs stringForKey:@"username_preference"]];
    NSString * passwordString = [NSString stringWithFormat:@"Content-Disposition: form-data; name=\"password\"\r\n\r\n%@", [prefs stringForKey:@"password_preference"]];
    NSString * apiString = [NSString stringWithFormat:@"Content-Disposition: form-data; name=\"api_key\"\r\n\r\n3eceaa7c-6d4d-41ab-be90-2a780e2d1961"];
    NSString * messageString = [NSString stringWithFormat:@"Content-Disposition: form-data; name=\"message\"\r\n\r\n%@", message];
    NSString * tagsString = [NSString stringWithFormat:@"Content-Disposition: form-data; name=\"tags\"\r\n\r\n%@", tags];
    NSString * latString = [NSString stringWithFormat:@"Content-Disposition: form-data; name=\"latitude\"\r\n\r\n%f", latitude];
    NSString * longString = [NSString stringWithFormat:@"Content-Disposition: form-data; name=\"longitude\"\r\n\r\n%f", longitude];
    NSString * boundaryString = [NSString stringWithFormat:@"\r\n--%@\r\n", boundary];
    NSString * boundaryStringFinal = [NSString stringWithFormat:@"\r\n--%@--\r\n", boundary];

    [postData appendData:[boundaryString dataUsingEncoding:NSUTF8StringEncoding]];
    [postData appendData:[userNameString dataUsingEncoding:NSUTF8StringEncoding]];
    [postData appendData:[boundaryString dataUsingEncoding:NSUTF8StringEncoding]];
    [postData appendData:[passwordString dataUsingEncoding:NSUTF8StringEncoding]];
    [postData appendData:[boundaryString dataUsingEncoding:NSUTF8StringEncoding]];
    [postData appendData:[apiString dataUsingEncoding:NSUTF8StringEncoding]];
    [postData appendData:[boundaryString dataUsingEncoding:NSUTF8StringEncoding]];
    //(...)
}

（sendImage 方法是 http://davidjhinson.wordpress.com/2009/06/01/posting-photos-using-objective-c/）

控制台也这样说：* Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '* -[UIImage length]: unrecognized selector sent to instance 0x3b28df0'

感谢您的帮助。也许我只是在代码中犯了一个愚蠢的错误，但请不要生气，因为我只是学习编程 2 1/2 周。

Answer 1

听起来您将 UIImage 传递给此方法，而不是 NSData 块。您可以尝试记录照片参数吗？

Answer 2

您遇到的具体错误是什么？换句话说，是什么让您认为您指出的行有错误？

如果崩溃，控制台打印的错误是什么？