Passing String Value of a NSManagedObject attribute to a new view controller - ios

Question

I have a tableView populated with NSString values from an NSFetchedResultsController. I have the cells configured to check/uncheck cells. That works perfectly.
I'm trying to configure the cells so clicking one of the labels within the cell triggers a segue to another view controller. I configured the label and threw a log statement in where I'd like to do the segue and everything works properly. When I add the segue, get no compiler errors, but it crashes at runtime with the follow error:
2015-05-31 08:09:04.656 MyApp[17682:1240919] -[UIViewController selectedItemPhoto:]: unrecognized selector sent to instance 0x7fa42b65d4e0
2015-05-31 08:09:04.694 MyApp[17682:1240919] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[UIViewController selectedItemPhoto:]: unrecognized selector sent to instance 0x7fa42b65d4e0'
I'm fairly certain I'm doing something startlingly stupid, but I'm stumped as to what. I welcome suggestions.
MyCustomCell.h:
#property (strong, nonatomic) IBOutlet UILabel *itemDescription;
#property (strong, nonatomic) IBOutlet UILabel *itemGroup;
#property (strong, nonatomic) IBOutlet UIImageView *itemImage;
FirstVC.m methods:
cellForRowAtIndexPath method
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
// implement custom cell
MyCustomCell *customCell = [tableView dequeueReusableCellWithIdentifier:#"customCell" forIndexPath:indexPath];
// Get a hold of myManagedObject from FRC
MyNSManagedObject *myObject = [self.fetchedResultsController objectAtIndexPath:indexPath];
// Configures 1st label to look like a hyperlink
customCell.itemDescription.text = myObject.itemDescription;
customCell.itemDescription.textColor = [UIColor blueColor];
customCell.itemDescription.userInteractionEnabled = YES;
// Enables gesture and sets demoObject to pass along via the segue called from labelTap
UITapGestureRecognizer *labelTapGesture = [[UITapGestureRecognizer alloc]initWithTarget:self action:#selector(labelTap)];
[customCell.itemDescription addGestureRecognizer:labelTapGesture];
self.demoObject = myObject;
// Configures 2nd label within customCell
customCell.itemGroup.text = myObject.itemGroup;
// add image to cell, already imported into Images.xcassets
NSString *imageName = [NSString stringWithFormat:#"%#-1.jpg", myObject.photo];
customCell.imageView.image = [UIImage imageNamed:imageName];
// The following code ensures random checkmarks don't appear when the user scrolls.
if ([self.selectedObjects containsObject:[self.fetchedResultsController objectAtIndexPath:indexPath]]) {
customCell.accessoryType = UITableViewCellAccessoryCheckmark;
} else {
customCell.accessoryType = UITableViewCellAccessoryNone;
}
return customCell;
}
didSelectRowAtIndexPath method
-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
self.selectedObject = [self.fetchedResultsController objectAtIndexPath:indexPath];
// Set the checkmark accessory for the selected row.
if ([tableView cellForRowAtIndexPath:indexPath].accessoryType == UITableViewCellAccessoryNone) {
[[tableView cellForRowAtIndexPath:indexPath] setAccessoryType:UITableViewCellAccessoryCheckmark];
[self.selectedObjects addObject:self.selectedObject];
[tableView deselectRowAtIndexPath:indexPath animated:YES];
} else {
[[tableView cellForRowAtIndexPath:indexPath] setAccessoryType:UITableViewCellAccessoryNone];
[self.selectedObjects removeObject:self.selectedObject];
[tableView deselectRowAtIndexPath:indexPath animated:YES];
}
// Enables save button if there are items in the selectedObjects array
if (self.selectedObjects.count > 0) {
[self.saveButton setEnabled:YES];
} else {
[self.saveButton setEnabled:NO];
}
}
labelTap method
- (void) labelTap {
// The "hyperlink" effect I'm trying to achieve works without the segue
NSLog(#"itemDescription tapped");
[self performSegueWithIdentifier:#"mySegue" sender:nil];
}
prepareForSegue method
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
if ([[segue identifier] isEqualToString:#"mySegue"] && self.demoObject != nil) {
// This line returns a value...
NSLog(#"self.demoObject = %#", self.demoObject.itemDescription);
// ...but it crashes here when it tries to set on the destinationViewController
SecondViewController *destinationViewController = [segue destinationViewController];
destinationViewController.selectedItemPhoto = self.demoObject.photo;
destinationViewController.selectedItemTitle = self.demoObject.itemDescription;
}
}
SecondViewController.h properties
// The photo is a string that references a filename in my app
#property (nonatomic, strong) NSString *selectedItemPhoto;
#property (nonatomic, strong) NSString *selectedItemTitle;

Answer 1

From the error it seems you did not set the class of your second view controller. It seems it is UIViewController and should be SecondViewController.
In your storyboard select the second view controller and set its class to SecondViewController.
Another advice is that in Objective C you should use introspection before casting an object. So in your code I would add:
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
if ([[segue identifier] isEqualToString:#"mySegue"] && self.demoObject != nil) {
// This line returns a value...
NSLog(#"self.demoObject = %#", self.demoObject.itemDescription);
// ...but it crashes here when it tries to set on the destinationViewController
if ([[segue destinationViewController] isKindOfClass:[SecondViewController class]]) {
SecondViewController *destinationViewController = (SecondViewController *)[segue destinationViewController];
destinationViewController.selectedItemPhoto = self.demoObject.photo;
destinationViewController.selectedItemTitle = self.demoObject.itemDescription;
}
}
}
In this way the segue won't happen but the app won't crash.

Answer 2

I figured it out! I had three issues (two were tied together):
Issue 1: Juan Catalan pointed out I didn't have my storyboard set for SecondViewController
Issue 2: Yuchen & luk2302 raised the issue of how I'm performing the segue.
Issue 3: I don't need prepareForSegue
Here's what I did:
1: I removed prepareForSegue.
2: I removed the storyboard segue.
2: I altered labelTap method to add a parameter for the labelTapGesture
- (void) labelTap:(UITapGestureRecognizer *)sender {
NSLog(#"stretchDescription tapped");
CGPoint location = [sender locationInView:self.view];
if (CGRectContainsPoint([self.view convertRect:self.tableView.frame fromView:self.tableView.superview], location)) {
CGPoint locationInTableview = [self.tableView convertPoint:location fromCoordinateSpace:self.view];
NSIndexPath *indexPath = [self.tableView indexPathForRowAtPoint:locationInTableview];
if (indexPath) {
self.demoObject = [self.fetchedResultsController objectAtIndexPath:indexPath];
DisplayStretchViewController *destinationViewController = [self.storyboard instantiateViewControllerWithIdentifier:#"SecondVC"];
// Set properties on destinationVC
destinationViewController.itemPhoto = self.demoObject.photo;
destinationViewController.itemTitle = self.demoObject.stretchDescription;
[self.navigationController pushViewController:destinationViewController animated:YES];
}
}
}
I also found this post extremely helpful:
UILabel with Gesture Recognizer inside UITableViewCell blocks didSelectRowAtIndexPath
Thank you to all for your input!