I know this question has been asked, but I have read the responses, adopted the fixes and still have an issue somewhere which I can't identify.
I have an IOS app which is similar in nature to email. It has an InboxVC which is a tableVC with a custom prototype cell which upon selection triggers a messageDetailVC.
The issue is that the messageDetailVC is triggered but the values are not being passed to it. I added log messages to evaluate the value in code before getting to Storyboard issues, and the variable being passed (messageID) has a NULL value.
Can someone tell me what I am missing or doing wrong? My code is:
InboxVC.m (snippet)
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
[tableView deselectRowAtIndexPath:indexPath animated:YES];
NSLog(#"%#: Message touched...", LOG_TAG);
messageDetail *mdvc = [[messageDetail alloc] init];
mdvc.messageID = #"123456789-1";
[self.navigationController pushViewController:mdvc animated:YES];
NSLog(#"%#: messageID value is = %#",LOG_TAG,mdvc.messageID);
//messageID has valid value here
}
messageDetail.h
#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>
#interface messageDetail : UIViewController
{
NSString *messageID;
}
#property (strong, nonatomic) NSString *messageID;
#property (strong, nonatomic) IBOutlet UITextView *body;
messageDetail.m
#import <Foundation/Foundation.h>
#import "messageDetail.h"
static NSString * LOG_TAG = #"messageDetailController";
#implementation messageDetail
#synthesize messageID;
#synthesize body;
- (void)viewDidLoad {
[super viewDidLoad];
body.text = messageID;
//debug messages
NSLog(#"%#:Added messageID as Body text", LOG_TAG);
NSLog(#"%#:Value of body.text is = %#", LOG_TAG, body.text);
NSLog(#"%#:Value of messageID is = %#", LOG_TAG, messageID);
//messageID has null value here
}
- (void) viewWillAppear:(BOOL)animated {
[self.navigationController setNavigationBarHidden:NO];
}
MainStoryboard:
I have a messageDetail view tied to the messageDetail sub class of UIViewController. There is a segue with identifier "s_msgDetail" from the prototype cell's selection event to the messageDetailVC (show). As I said above the messageDetailVC appears, just not with the body.text being set to the value of "messageID".
You are setting the messageID on the wrong instance of your messageDetail view controller. Since you are using storyboards, the storyboard is already creating and presenting an instance of messageDetail for you. But, in tableView:didSelectRowAtIndexPath: you are creating a second one and presenting it. (I'm surprised you're not getting a bunch of runtime animation warnings when doing that.)
You should be setting messageID in prepareForSegue:sender: like this:
- (void) prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
if ([segue.identifier isEqualToString:#"s_msgDetail"]) {
messageDetail * vc = (messageDetail *) segue.destinationViewController;
NSIndexPath * indexPath = [self.tableView indexPathForSelectedRow];
vc.messageID = /* use indexPath to get data from messages collection */;
}
}
You have to use prepareForSegue to pass value to another view Controller
Related
I am trying to pass selected cell text from CategoryViewController to DescribeViewController. But it does not call the method in the DescribeViewController method.
CategoryViewController.h
#import <UIKit/UIKit.h>
#protocol CategoryViewControllerDelegate <NSObject>
- (void)didSelectRow:(NSString *)cellDataString;
#end
#interface CategoryViewController : UIViewController<UITableViewDelegate, UITableViewDataSource>
#property (weak, nonatomic) id<CategoryViewControllerDelegate> delegate;
#end
CategoryViewController.m
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCell *cell = [categoryTableView cellForRowAtIndexPath:indexPath];
NSString *cellText = cell.textLabel.text;
[self.delegate didSelectRow:cellText];
[[self navigationController] popViewControllerAnimated:YES];
}
DescribeViewController.h
#import <UIKit/UIKit.h>
#import "CategoryViewController.h"
#interface DescribeViewController : ProductAwareBaseViewController<UITextFieldDelegate, CategoryViewControllerDelegate>
The following didSelectRow method is not getting called. I could not able to find out the root of the problem.
DescribeViewController.m
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view.
CategoryViewController *popoverTableViewController = [[CategoryViewController alloc] init];
popoverTableViewController.delegate = self;
}
- (void)didSelectRow:(NSString *)cellDataString
{
self.cellDataString = cellDataString;
}
ProductAwareBaseViewController.h
#import UIKit;
#class Product;
#interface ProductAwareBaseViewController : UIViewController
#property (nonatomic, strong) Product *product;
#end
ProductAwareBaseViewController.m
#import "ProductAwareBaseViewController.h"
#import "Product.h"
#interface ProductAwareBaseViewController ()
#end
#implementation ProductAwareBaseViewController
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
if ([segue.destinationViewController isKindOfClass:[ProductAwareBaseViewController class]]) {
ProductAwareBaseViewController *vc = (ProductAwareBaseViewController *)segue.destinationViewController;
vc.product = self.product;
}
}
#end
Try setting the delegate object in didSelectRow. And call that delegate method after that. Because delegate is weak, may be it is released from the memory.
CategoryViewController *popoverTableViewController = [[CategoryViewController alloc] init];
popoverTableViewController.delegate = self;
UITableViewCell *cell = [categoryTableView cellForRowAtIndexPath:indexPath];
NSString *cellText = cell.textLabel.text;
[self.delegate didSelectRow:cellText];
[[self navigationController] popViewControllerAnimated:YES];
Most common reason for delegate method not being called is dealing with incorrect objects.
Ensure that CategoryViewController object created from
DescribeViewController is the same which you are presenting on
screen and that the delegate is being set on the same object. I truly believe you are creating a new CategoryViewController object and setting delegate on that.
In DescribeViewController, before calling delegate, check the
existence of delegate and that it implements the protocol method (if
its an optional method). This is a safety check, you can also put a NSLog statement to double check if your delegate exists or not. You are failing here.
->
if (delegate && [delegate respondsToSelector:(didSelectRow:)]) {
[self.delegate didSelectRow:cellText];
}
PS: If you are segueing from DescribeViewController to CategoryViewController then you set delegate in prepareForSegue:.
Follow these guidelines and I am sure you would be able to fix your issue!
try
#property (nonatomic, weak) id <CategoryViewControllerDelegate> delegate;
for declaring your delegate.
EDITED
try for checking the delegate is returning some value or not.
By this, whenever yo are setting the values.
if(self.delegate && [self.delegate respondsToSelector:#selector(didSelectRow:)])
{
[self.delegate didSelectRow:(NSString *) cellDataString];
}
and also if you are using the segue to transfer the data between two controllers then check there for the delegates.
-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
DescribeViewController *obj = (DescribeViewController *)segue.destinationViewController;
obj.delegate =self;
}
i think this will help you.
In tableViewControllerA.h I declare a delegate ,and in tableViewControllerA.m I implement the method when click a cell of the tableView, A will pass the value to B, and execute the perfromSegueWithIdentifier to jump to tableViewControllB,in tableViewControllB.m the getting method is called, and I get the value, but after the viewDidLoad() method call, the value become nil. Please help me to solve the problem.By the way , the property of the value is strong,nonatomic.
DTZHomeTableViewController.h
#import <UIKit/UIKit.h>
#import "PassData.h"
#protocol PassDataDelegate
-(void)passData:(PassData*) dataToProgram;
#end
#interface DTZHomeTableViewController :
UITableViewController<UITableViewDelegate,UITableViewDataSource>
#property(assign,nonatomic) id<PassDataDelegate> dataDelegate;
#end
PassData is an user-defined class
DTZHomeTableViewController.m
-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
ProgramTableViewController *programViewController=
[[ProgramTableViewController alloc]init];
self.dataDelegate=programViewController;;
PassData *jump=[[PassData alloc]init];
jump.livingStatus=YES;
jump.role=0;
jump.index=indexPath.row;
jump.curOnlineNum=305605;
[self.dataDelegate passData:jump];
[self performSegueWithIdentifier:#"showSelectedProgram" sender:self];
}
ProgramTableViewController.h
#import <UIKit/UIKit.h>
#import "DTZHomeTableViewController.h"
#interface ProgramTableViewController :
UITableViewController<PassDataDelegate,UITableViewDataSource,UITableViewDelegate>
#property(strong,nonatomic) PassData * dataFromHome;
#end
ProgramTableViewController.m
#implementation ProgramTableViewController
- (void)viewDidLoad {
[super viewDidLoad];
NSLog(#"view did load%#",self.dataFromHome); // log :null
}
- (void) passData:(PassData *)dataToProgram
{
self.dataFromHome=dataToProgram;
}
#end
Delegation isn't the proper way to pass data to a segued view controller. Instead, you want to pass the data in prepareForSegue:sender:
Remove the protocol and delegate.
Add properties to your ProgramTableViewController for the data you want to pass.
#property (nonatomic, assign) BOOL livingStatus;
#property (nonatomic, assign) NSInteger role;
#property (nonatomic, assign) NSInteger row;
#property (nonatomic, assign) NSInteger curOnlineNum;
In prepareForSegue:sender:, set the ProgramTableViewController's passed properties to the values associated with the selected row:
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)__unused sender
{
if ([[segue identifier] isEqualToString:#"showDetail"])
{
NSIndexPath *indexPath = [self.tableView indexPathForSelectedRow];
ProgramTableViewController *controller = (ProgramTableViewController *)[segue destinationViewController];
controller.livingStatus = YES;
controller.role = 0;
controller.row = indexPath.row;
controller.curOnlineNum = 305605;
}
}
You shouldn't allocate and init ProgramTableViewController in tableView:didSelectRowAtIndexPath:. Your segue will instantiate the destination view controller for you.
You don't even need to have a tableView:didSelectRowAtIndexPath: method. You can create a push segue from the tableViewCell to ProgramTableViewController, right within Storyboard. Give the segue an identifier (such as "showDetail"). Then in prepareForSegue, you assign the values, as I explained.
When you tap on that row, the segue will create a ProgramTableViewController, set the parameters, and present it for you.
I have FirstViewController and SecondTableViewController. In SecondTableViewController.m, I create a cell in the cellForRow... method where the cell.textLabel.text is a string from an NSInteger property ("count") of the SecondTableViewController.
I would like a button in FirstViewController to increment the value of count.
I've tried making a property of FirstViewController and then using that:
#property SecondTableViewController *viewController;
and
- (IBAction)buttonTouched:(id)sender {
self.viewController.count++;
[self.viewController.tableView reloadData];
}
But this way isn't working. count is still its original value of zero. I've also reloaded the table in viewWillAppear and still nothing. How can I do this?
Count being used as a property may be where you are going wrong because count is a method that returns the number of objects in an array that is found in foundation framework. Also keep in mind that if you are storing a integer into a string object try storing it in this format.
cell.textlabel.text = [NSString stringWithFormat: #"%i", count];
Hope this helps
Try following
firstViewController.h
#interface DMFirstViewController : UIViewController
#property (nonatomic, strong) DMSecondViewController * secondController;
- (IBAction)buttonPressed:(id)sender;
#end
firstViewController.m
- (IBAction)buttonPressed:(id)sender
{
++self.secondController.count;
[self.navigationController pushViewController:self.secondController animated:YES];
}
secondViewController.h
#property (nonatomic) int count;
secondViewController.m
-(void)viewWillAppear:(BOOL)animated {
[super viewWillAppear:animated];
NSLog(#"%d", self.count);
}
EDIT
Check out those two images and implement the similar logic and get the solution.
----- END OF NEW EDIT -----
OLD
I think you haven't assigned and allocated memory for SecondTableViewController reference i.e, self.viewController of FirstViewController in its viewDidLoad method i.e,
-(void) viewDidLoad //In FirstViewController
{
self.viewController = [[SecondTableViewController alloc] init];
}
and pushed the same reference on to the stack of navigationController after performing button taps to increase the count of count variable of SecondTableViewController.
If you are not clear, comment.
I have a simple app which connects to a web server and the web server returns a JSON value.
I am trying to send the JSON value from ViewController1 to "linkController", however when I send the sender over to ViewController2 the sender value is null?
Here is my code:
-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
if ([segue.identifier isEqualToString:#"linkControllerSegue"]) {
linkController *lc = [segue destinationViewController];
lc.introString = sender;
}
}
This is part of my linkController.h file:
#interface linkController : UIViewController
{
// succes view outlets
IBOutlet UILabel *short_url;
IBOutlet UILabel *full_url;
UIDataDetectorTypes *json;
}
#property (weak, nonatomic) NSDictionary *introString;
And my linkController.m file:
#synthesize introString;
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view.
NSLog(#"%#", introString);
}
The segue is being called through the code:
[self performSegueWithIdentifier:#"linkControllerSegue" sender:nil];
The NSLog in the viewDidLoad method returns: (null).
Is there anything I am doing wrong?
Many Thanks,
Peter
Try:
lc.introString = short_url.text;
instead of:
lc.introString = sender;
I have a UITableView, which when I select a row, I want to segue to another view, where the details of the tank are displayed... The segue happens, but the delegate does not send the object etc over... I think I have my knickers in a twist over where the delegate is declared/synthesized and implemented etc...
Here is where I declare the delegate in the header file of the UITableViewController:
#class iTanksV2ListViewController;
#protocol iTanksV2ListViewControllerDelegate
- (void) iTanksListViewController:(iTanksV2ListViewController *) sender choseTank:(tank *)tank;
#end
#interface iTanksV2ListViewController : UITableViewController
#property (weak, nonatomic) id <iTanksV2ListViewControllerDelegate> delegate;
#end
and this is what I have in the UITableViewControllers m file:
#implementation iTanksV2ListViewController
#synthesize delegate = _delegate;
- (void)viewDidLoad
{
[super viewDidLoad];
self.tankTableView.delegate = self;
self.tankTableView.dataSource = self;
}
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
self.selectedTank = [self.tanks objectAtIndex:indexPath.row];
[self.delegate iTanksListViewController:self choseTank:self.selectedTank];
}
...and then here is the code I have for the delegate in the DetailViewController implementation file...
#interface tankDetailViewController () <iTanksV2ListViewControllerDelegate>
#end
-(void)iTanksListViewController:(iTanksV2ListViewController *)sender choseTank:(id)tank
{
self.tankToShow = tank;
}
All the other variables etc are declared, I have left them out in the hope it makes things clearer - the code compiles, and the segue happens but the delegate doesn't seem to do anything!!!
You mention segues so I'm assuming you're using a storyboard. If that's true, forget about delegates for this purpose. A delegate is supposed to be an object that performs some action for another but all you need is data transfer.
I suggest using the prepareForSeque: method instead in your iTanksV2ListViewController class. Keep the line that sets self.selectedTank when a row is tapped but then put something like this in prepareForSegue:
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
tankDetailViewController *next = (tankDetailViewController *)[segue destinationViewController];
next.tankToShow = self.selectedTank;
}