Transferring Data Back to Original View - objective-c

Question

So I am able to transfer the data from the first view to the second view like this:
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
if ([segue.identifier isEqualToString:#"Check Mark Segue"])
{
NSLog(#"Transfering Data");
AutoRenewDrop *controller = segue.destinationViewController;
controller.transferData = self.renewDate.text;
}
}
However, I try to transfer a new value back to renewDate.text when the user hits done and the transferData is working correctly but the renewDate.text does not change. Here is the code that I am using to transfer the data back:
-(IBAction)done:(UIStoryboardSegue *)segue {
[self.navigationController popViewControllerAnimated:YES];
AddR *add = [[AddR alloc] init];
add.renewDate.text = transferData;
}
Can someone tell me how to fix this?

Answer 1

You need to add a property that contain a reference of the first view into the second view :
#interface AutoRenewDrop
#property(weak, nonatomic) AddR *callerView;
#end
And then in the done method of the second view you can just update the variale in the caller view :
-(IBAction)done:(UIStoryboardSegue *)segue {
[self.navigationController popViewControllerAnimated:YES];
callerView.renewDate.text = transferData;
}
Of course when you instantiate the second view you will have to set the reference, in this way :
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
if ([segue.identifier isEqualToString:#"Check Mark Segue"])
{
NSLog(#"Transfering Data");
AutoRenewDrop *controller = segue.destinationViewController;
controller.transferData = self.renewDate.text;
controller.callerView = self; //Here, you are passing the reference to this View
}
}

Answer 2

You should use a delegate.
You can read a pretty good tutorial about protocols and delegates here.
Lets say you have 2 ViewControllers - VC1 and VC2, and lets say that VC1 displays VC2.
In VC2.h
#protocol VC2Delegate <NSObject>
- (void)updateData:(id)theData;
#end
#interface
#property (nonatomic, weak) id<VC2Delegate> delegate;
#end
In VC2.m
#syntesize delegate;
- (void)done
{
[delegate updateData:myData];
}
In VC1.h
#interface VC1 : UIViewController<VC2Delegate>
In VC1.m
- (void)goToVC2
{
VC2 *vc2 = [[VC2 alloc] init];
vc2.delegate = self;
// present vc2
}
- (void)updateData:(id)data
{
// update what you need
}