How to pass indexPath from segue to destination view?

问题

I have two buttons in a custom layout collectionView's footer. I want to pass the indexPath of the footerView to destinationView class when user taps the button. I wrote my code in a typical way which I succeeded before. However, in some reason, whenever I tap the button it crashes.

I tried different approaches for each button to accomplish this job but neither worked. I have set destinationView's class to the right class in a storyboard. Please somebody help me. Any help with code example will be very appreciated since English is not my first language. Thank you.

Here's my code

    // perform segue passing indexPath information
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {

    // approach 1 : pass dictionary
    if([[segue identifier] isEqualToString:@"SeeAllPictures"]) {
        Footer *footerView = (Footer *)((UIButton *)sender).superview;

        // debug code : working well
        NSLog(@"perform segue from indexpath {%ld - %ld}", (long) footerView.indexPath.section, (long) footerView.indexPath.row);

        SeeAllPicture *destVC = (SeeAllPicture *)[segue destinationViewController];
        NSDictionary *indexPathDic = @{@"key1":footerView.indexPath};
        // crashes at below line
        destVC.indexPathDic = indexPathDic;
    }
    // approach 2 : pass indexPath.section, the NSInteger value
    else if([[segue identifier] isEqualToString:@"GoToDiary"]) {
        Footer *footerView = (Footer *)((UIButton *)sender).superview;

        // debug code : working well
        NSLog(@"perform segue from indexpath {%ld - %ld}", (long) footerView.indexPath.section, (long) footerView.indexPath.row);
        Diary *destVC = (Diary *)[segue destinationViewController];
        // crashes at below line
        destVC.section = footerView.indexPath.section;
    }
}

below is header of one of the destination class

#import <UIKit/UIKit.h>

@interface SeeAllPicture : UIViewController

@property (strong, nonatomic) IBOutlet UILabel *titleLabel;
@property (strong, nonatomic) NSDictionary *indexPathDic;

@property NSInteger section;

@end

And this is the message when my app crashes

Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[UINavigationController setIndexPathDic:]: unrecognized selector sent to instance 0x7ff8c8c4f140'
*** First throw call stack:
(
    0   CoreFoundation                      0x000000010f7f7a75     __exceptionPreprocess + 165
    1   libobjc.A.dylib                     0x000000010f490bb7     objc_exception_throw + 45
    2   CoreFoundation                      0x000000010f7fed1d -    [NSObject(NSObject) doesNotRecognizeSelector:] + 205
    3   CoreFoundation                      0x000000010f7569dc     ___forwarding___ + 988
    4   CoreFoundation                      0x000000010f756578     _CF_forwarding_prep_0 + 120
    5   InfanTree                           0x000000010ea1113b -    [ViewController prepareForSegue:sender:] + 635
    6   UIKit                               0x000000011037e3cc -    [UIStoryboardSegueTemplate _perform:] + 151
    7   UIKit                               0x000000010fe2ba22 -    [UIApplication sendAction:to:from:forEvent:] + 75
    8   UIKit                               0x000000010ff32e50 -[UIControl     _sendActionsForEvents:withEvent:] + 467
    9   UIKit                               0x000000010ff3221f -[UIControl     touchesEnded:withEvent:] + 522
    10  UIKit                               0x00000001101d9e80     _UIGestureRecognizerUpdate + 9487
    11  UIKit                               0x000000010fe71856 -[UIWindow     _sendGesturesForEvent:] + 1041
    12  UIKit                               0x000000010fe72483 -[UIWindow     sendEvent:] + 667
    13  UIKit                               0x000000010fe3efb1 -    [UIApplication sendEvent:] + 246
    14  UIKit                               0x000000010fe4c227     _UIApplicationHandleEventFromQueueEvent + 17700
    15  UIKit                               0x000000010fe2723c     _UIApplicationHandleEventQueue + 2066
    16  CoreFoundation                      0x000000010f72cc91     __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17
    17  CoreFoundation                      0x000000010f722b5d __CFRunLoopDoSources0 + 269
    18  CoreFoundation                      0x000000010f722194 __CFRunLoopRun + 868
    19  CoreFoundation                      0x000000010f721bc6 CFRunLoopRunSpecific + 470
    20  GraphicsServices                    0x0000000112950a58 GSEventRunModal + 161
    21  UIKit                               0x000000010fe2a580 UIApplicationMain + 1282
    22  InfanTree                           0x000000010ea1b7c3 main + 115
    23  libdyld.dylib                       0x0000000113211145 start + 1
)

回答1:

It looks like your SeeAllPicture view controller is embedded in a UINavigationController. In this case destinationViewController on the segue is that navigation controller NOT your SeeAllPicture view controller.

You probably want the topViewController of the destinationViewController

UINavigationController *navigationVC = (UINavigationController *)[segue destinationViewController];
SeeAllPicture *destVC = navigationVC.topViewController;

回答2:

as rdelmar says its fine, but to have it crash free you could checko for the Class with isKindOfClass:. Anyways, just set a breakpoint after SeeAllPicture *destVC = (SeeAllPicture *)[segue destinationViewController]; and check the console in XCode, here u will se that the class is kind of UINavigationController :)

来源：https://stackoverflow.com/questions/29833284/how-to-pass-indexpath-from-segue-to-destination-view