如何在 iOS 的 Instagram 上分享图片

Finally I got the answer. you can not directly post an image on instagram. You have to rediredt your image with UIDocumentInteractionController.

@property (nonatomic, retain) UIDocumentInteractionController *dic;    

CGRect rect = CGRectMake(0 ,0 , 0, 0);
UIGraphicsBeginImageContextWithOptions(self.view.bounds.size, self.view.opaque, 0.0);
[self.view.layer renderInContext:UIGraphicsGetCurrentContext()];
UIGraphicsEndImageContext();
NSString  *jpgPath = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents/test.igo"];

NSURL *igImageHookFile = [[NSURL alloc] initWithString:[[NSString alloc] initWithFormat:@"file://%@", jpgPath]];
self.dic.UTI = @"com.instagram.photo";
self.dic = [self setupControllerWithURL:igImageHookFile usingDelegate:self];
self.dic=[UIDocumentInteractionController interactionControllerWithURL:igImageHookFile];
[self.dic presentOpenInMenuFromRect: rect    inView: self.view animated: YES ];


- (UIDocumentInteractionController *) setupControllerWithURL: (NSURL*) fileURL usingDelegate: (id <UIDocumentInteractionControllerDelegate>) interactionDelegate {
     UIDocumentInteractionController *interactionController = [UIDocumentInteractionController interactionControllerWithURL: fileURL];
     interactionController.delegate = interactionDelegate;
     return interactionController;
}

NOTE : once you redirect to instagram app you can not back to your app. you have to open your app again

Download source from here