segue: destination view controller weirdness - ios

Question

In my app, I use a storyboard and segues, and I often pass data to the destination view controller before doing the segue, as follows:
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
if ([segue.destinationViewController respondsToSelector:#selector(setMyData:)]) {
[segue.destinationViewController performSelector:#selector(setMyData:)
withObject:myData];
}
}
It works everywhere except in one place. The selector gets called, the data gets set, but when the segue completes and the destination controller appears, it doesn't have the data I just set. After printing the view controller's id in both the source and destination view controllers, I found that the segue.destinationViewController in the code above is a DIFFERENT instance of the view controller than the one that gets displayed. What's going on here?
[UPDATE 1]
I looked into the lifecycle of the destination view controller, and it first gets loaded during the segue execution, but AFTER I set the property on it! This means, that when I call performSelector on it, the view controller object is not initialized! This is why the data I set doesn't stick. t don't understand why is this the case, and why this same approach works in the other parts of my app.
[UPDATE 2]
Posting the code of setMyData by request. At first I didn't have this method at all, because locationToOpen is a public property. I only added it to ensure it gets called and to print the debug info.
- (void)setMyData:(MyData *)myData
{
DLog(#"self: %#", (id)self);
_myData = myData;
}

Answer 1

I would do it as follows -
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
if ([segue.identifier isEqualToString:#"NextSegue"])
{
DestinationViewController *dest = [segue destinationViewController];
dest.myData = self.myData;
}
}
And in the DestinationViewController.h, you should create a property -
#import <UIKit/UIKit.h>
#interface DestinationViewController : UIViewController
#property (nonatomic, strong) NSObject *myData;
#end
And also, make sure to synthesize the myData property in DestinationViewController.m -
#interface DestinationViewController ()
#end
#implementation DestinationViewController
#synthesize myData = _myData;
// other methods here
#end

Answer 2

I had this same issue. It turned out for me that the target ViewController property I was setting in my prepareForSegue: code was declared as weak because I had copied and pasted the property from one that InterfaceBuilder auto-created, but mine was not a Storyboard object. So my property was being released and zeroed by ARC on exit from prepareForSegue:. Making it a non-weak property fixed it.

Answer 3

I had a similar problem where the ViewController I was doing the segue to changed at some odd point,
after a looking around a bit it seems that the segue created a new ViewController.
To solve the data passing problem I used notifications.

Answer 4

I know this thread is old and solution should be found. But since the final solution is not posted here, I would like to list one of the possible root cause (which is the one in my case). I had the same issue, trying to set the variable in the destination view controller of the segue. The root cause is that I forgot to instantiated ([[Class alloc]init]) the object variable. I need it in my case because I am setting the properties of the object instead of pointing to other object. Hope this help.