我无法使用 ios App 在 Instagram 上发布我的照片。我从 stackoverflow 上的帖子中获得了以下代码，但它不起作用。Instagram 启动时，显示错误无法打开文件。请帮助我。
NSURL *instagramURL = [NSURL URLWithString:@"instagram://location?id=1"];
if ([[UIApplication sharedApplication] canOpenURL:instagramURL]) {
NSString *documentsDirectory = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents"];
NSString *savedImagePath = [documentsDirectory stringByAppendingPathComponent:@"Image.ig"];
NSData *imageData = UIImagePNGRepresentation([UIImage imageNamed:@"Icon.png"]);
[imageData writeToFile:savedImagePath atomically:YES];
NSURL *imageUrl = [NSURL fileURLWithPath:savedImagePath];
docController = [[UIDocumentInteractionController alloc] init];
docController.delegate = self;
[docController retain];
docController.UTI = @"com.instagram.photo";
[docController setURL:imageUrl];
[docController presentOpenInMenuFromRect:CGRectZero inView:self.view animated:YES];
}else{
UIAlertView *errorToShare = [[UIAlertView alloc] initWithTitle:@"Instagram unavailable " message:@"You need to install Instagram in your device in order to share this image" delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
[errorToShare show];
[errorToShare release];
}