I am saving an image in my ViewController, and want to pass it to the next one during segue, however doing this causes an infinite loop.
Here is my code:
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
if ([[segue identifier] isEqualToString:#"next"])
{
ReviewViewController *rvc = [segue destinationViewController];
[rvc setFilename:self.filename];
}
}
the setFilename method in ReviewViewController simply looks like this:
- (void)setFilename:(NSString *)filename{
NSLog([NSString stringWithFormat:#"Setting filename to: %#",filename]);
self.filename = filename;
}
That log statement fires off ad-infinitum when I add in the prepareForSegue method. If I remove it, the transition is fine.
What is going on?
The answer, as many pointed out in the comments, is that self.filename = actually calls [self setFilename], which is what I had called my method.
This is fixed by either renaming my setFilename method, or doing the assignment via _filename = instead.
Related
I have made a segue passing a string which tells the next view controller which instance to parse the CoreData for. The problem is, I am using some code that calls init methods and the sent string is not initialized when it is called. However, the segue is working when I display the string in the destination view controller's viewDidLoad
- (id)init
{
self = [super init];
if (self)
{
[self initFakeData];
}
return self;
}
When that initFakeData method is called it sets up a graph and needs the exercise to hold a valid value
- (void)initFakeData
{
NSString *myExercise=exercise; //returns nil
if (myExercise==nil)
{
myExercise=#"Default";
}
}
Meanwhile...
-(void)viewDidLoad{
NSString *myExercise=exercise; //returns value
}
exercise is a property that is initialized by the previous view controller in a tableview
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
NSIndexPath *indexPath = [self.tableView indexPathForSelectedRow];
if ([segue.identifier isEqualToString:#"showGraph"]) {
JBLineChartViewController *destViewController = segue.destinationViewController;
NSString *myExericse=[NSString stringWithFormat:#"%#", [[_exercises valueForKey:#"exercise"]objectAtIndex:indexPath.row]];
NSLog(#"%#",myExericse);
destViewController.exercise = myExericse;
}
}
The behaviour is correct because during init the exercise in JBLineChartViewController was not set. If you need the exercise attribute in the init method to set certain behaviour that have to be before viewDidLoad, my suggestion is to not use segue but do a designated initWithExercise and push the controller in code. Maybe like this:
- (IBAction)chartButtonPressed:(id)sender {
JBLineChartViewController *vc = [[ShopViewController alloc]initWithExercise:#"EXERCISE_STRING_HERE"];
[self showViewController:vc sender:self];
}
The new view controller is allocated and initialized before prepareForSegue is called. Anything you need to do with CoreData should be done in viewDidLoad. Or you can do it later, e.g. in viewWillAppear or viewDidAppear.
I am building an article reading app using storyboards.
I am also
using AMSlideMenu Library for the main menu. I am facing an problem that is, i want to
pass different url values when user click on different rows in AMSlideMenu.
here is my storyboad :
here is my code:
-(NSString *)segueIdentifierForIndexPathInLeftMenu:(NSIndexPath *)indexPath
{
NSString *idetifier = #"firstSegue";
// ysTableViewController *str;
switch (indexPath.row) {
case 0:
urlString = #"http://example.com/1";
break;
case 1:
urlString = #"http://example.com/2";
break;
case 2:
urlString = #"http://example.com/3";
break;
default:
urlString = #"http://example.com/4";
break;
}
return idetifier;
}
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
// Make sure your segue name in storyboard is the same as this line
if ([[segue identifier] isEqualToString:#"firstSegue"])
{
ysTableViewController *controller = (ysTableViewController *)segue.destinationViewController;
NSLog(#"asgasfg-----%#",urlString);
controller.Mainlinks = urlString;
}
}
You can create a new UIViewController inside prepareForSegue method.
— YourTableViewController *newObj= [[YourTableViewController alloc]init];
- newObj.value=#"your value";
By This way u can pass your value.
I got over the problem by using NSUserDefaults temporarily but still it not a proper solution. Still looking for a proper method to pass parameters b/w classes.
Make a subclass of AMSlideMenuLeftTableViewController or AMSlideMenuRightTableViewController (if you don't have already),
and implement following method
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
UINavigationController *destNC = segue.destinationViewController;
UIViewController *destVC = nc.viewControllers.firstObject;
if ([segue.identifier isEqualToString:#"firstSegue"])
{
FirstViewController *vc = (FirstViewController *)destVC;
// pass your data to vc
// e.g.
vc.title = #"I'm from first row";
} else if ([segue.identifier isEqualToString:#"secondSegue"]) {
// same for others
//...
}
}
I'd like to pass some object from one view (number 2) to view number 1. View 1 triggers view 2 and before that in "prepareForSeque" I'm passing "self" to the second view and store it in variable "delegate". After some time I'd like to pass back new created object to view 1 and I'm trying to achieve it but I got an error that method is not visible for this interface. How to pass created object to the mother view triggering method?
When I declare #property someObject and synthetize it, it works ok using delegate. Is there another option or am I forced to use delegate?
Code:
- (IBAction)saveAndClose:(id)sender {
KwejkModel *mod = [[KwejkModel alloc] init];
((ViewController *)self.delegate).model = mod;
}
It works ok, but is there another option triggering method not using the property? Like this:
[((ViewController *)self.delegate) someMethod];
but here is an error.
Here is my code:
VIEW 1
-(void) prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
if ([segue.identifier isEqualToString:#"addItemSeque"]) {
ScrollViewViewController *destViewController = segue.destinationViewController;
destViewController.delegate = self;
}
}
-(void) addNewPosition:(KwejkModel *)newKwejk
{
//for testing only this
[modelArray count];
}
VIEW 2:
- (IBAction)saveAndClose:(id)sender {
KwejkModel *mod = [[KwejkModel alloc] init];
// ((ViewController *)self.delegate).model = mod;
//it crashes here with error:-[NSPlaceholderString initWithString:]: nil argument' but it sees method from VIEW 1
[self.delegate addNewPosition:mod];
}
Try this link: Passing Data between View Controllers
Take a look at the first answer under Passing Data Back.
I have two view controllers: CropImageViewController and ImageCropperViewController
In CropImageViewController I have this method:
-(void) prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
NSLog(#"prepareForSegue called");
if([segue.identifier isEqualToString:#"goBack"])
{
NSLog(#"processedText = %#",self.processedText);
[segue.destinationViewController setProcessedText:self.processedText];
}
}
Then, in ImageCropperViewController, I have this:
-(void)viewWillAppear:(BOOL)animated
{
NSLog(#"view will appear called");
//self.processedImageLabel.text = self.processedText;
NSLog(#"processedText = %#",self.processedText);
NSLog(#"testLabel: %#",self.testField.text);
}
This is the console output. For some reason, "processedText" is always NULL no matter what.
2014-05-23 16:51:43.488 ImageCropper[9294:60b] prepareForSegue called
2014-05-23 16:51:43.490 ImageCropper[9294:60b] processedText = E33
===..., ____
2014-05-23 16:51:43.493 ImageCropper[9294:60b] view will appear called
2014-05-23 16:51:43.494 ImageCropper[9294:60b] processedText = (null)
I see your segue "goBack". Are you come back after pushed CropImageViewController from ImageCropperViewController?
So in this case you shouldn't use a segue. You should write an IBAction for your button (or i don't know what you have to come back) and when you press it do:
[self popViewControllerAnimated:YES];
but before this, you should call the delegate to pass the new value:
[_delegate changeProcessedText:self.processedText];
Obviously i assume that you know how implement a delegation pattern.
Another way could be use KVO, so observing from the first viewController, the processedText.text value in the second viewController.
i've been fixing this problem for a few days. but can't seem to get it..
help me out ..
let me explain my situation. Basically, i have navigation controller that contains table view controller and view controller. and i'm making simple phone book app.
And, i have a directory entry declared in extension class
#interface DetailViewController ()
#property DirectoryEntry *dirEntry;
#end
And, in table view, when you click the button it will transfer some data through segue
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
DetailViewController *detailCV = [segue destinationViewController];
if ([segue.identifier isEqualToString:#"cellToDetail"]) {
[detailCV setDirEntry: [self.pbArray objectAtIndex:[self.tableView indexPathForSelectedRow].row]];
} else {
detailCV.dirEntry = nil;
}
//designate delegate !!!
detailCV.delegate = self;
}
My Problem occurs when it execute detailCV.dirEntry = nil; it will call my setter in viewController. it says EXC_BAD_ACCESS
-(void) setDirEntry:(DirectoryEntry *) dirEntry {
self.dirEntry = dirEntry;
}
Thank you in advance..
It's not an EXC_BAD_ACCESS so much as the OS killing your app for smashing the stack. This method is recursing infinitely:
-(void) setDirEntry:(DirectoryEntry *) dirEntry {
self.dirEntry = dirEntry;
}
Your use of dot notation expands to a setter which should make this more clear.
-(void) setDirEntry:(DirectoryEntry *) dirEntry {
[self setDirEntry:dirEntry];
}
Set the instance variable directly, or let the compiler handle it. Properties in class extensions are automatically synthesized.