I used IB to create a UITableViewController in Storyboard. And I set the UITableview's delegate to be its controller. The UITableView has static cells. Just 2 sections. First section has 3 non-selectable rows. And last section has 1 row which is selectable. I set this all in IB only.
Then I implemented this method in the UITableViewController.
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
NSLog(#"SELECTED");
if (indexPath.section == 1 && indexPath.row == 0) {
//login and report the result
[self login];
}
}
When I select the only row in the 2nd section, this above method is not getting called. What could have gone wrong. I have double checked the delegate setups in outlets inspector of UITableView as well. Everything is fine!
Do you see the NSLog statement in the console? How about in viewDidAppear, NSLog(#"Delegate: %#",tableView.delegate)
See if you're getting NULL in the console.
You know that the dataSource is connected right, or else you wouldn't have any cells visible. It's got to be your delegate connection =)
Just do this:
Control drag you tableView from Storyboard to viewcontroller .h file, create #property for ex. tableView. Add again to .h file. Then in .m file in
viewDidLoad write this:
-(void)viewDidLoad{
//your other code
self.tableView.delegate = self;
self.tableView.dataSource = self;
//other code ...
}
I prefer to use tblView for property name, because you will see warning that tableView hides instance. Hope this help.
Related
I would like to call a method when a UITableViewCell is selected/tapped. I could do it easily with a static table view, but it requires a UITableViewController which is not good for me in this case, therefore I'm using a normal vc.
I have 10 specified methods like this:
- (void) methodOne {
NSLog(#"Do something");
}
- (void) methodTwo {
NSLog(#"Do something");
}
....
And I would like to call the methodOne when the first cell was tapped, call the methodTwo when the second cell was tapped and so on..
As a first step I set the numberOfRowsInSection to return 10 cells, but have no idea how could I connect the selected cells with the methods. Is there any quick way to do it? It would be a dirty solution to create 10 custom cells and set the every method manually for the custom cells, and there is no free place for it.
You can create an array of NSStrings with method names in the order they should be called from their corresponding UITableViewCells.
NSArray *selStringsArr = #[#"firstMethod", #"secondMethod", #"thirdMethod];
Then create a selector in tableView:didSelectRowAtIndexPath: from the strings array and call it using performSelector:.
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
NSString *selString = selStringsArr[indexPath.row];
SEL selector = NSSelectorFromString(selString);
if ([self respondsToSelector:#selector(selector)]) {
[self performSelector:#selector(selector)];
}
}
Of course, there are some limitations to using performSelector: which you can read here.
You can use this method for whenever any cell is tapped on the table view
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
NSInteger selectedRow = indexPath.row; //this is the number row that was selected
switch (selectedRow)
{
case 0:
[self methodOne];
break;
default:
break;
}
}
Use selectedRow to identify which row number was selected. If the first row was selected, selectedRow will be 0.
Don't forget to set the table view's delegate to your view controller. The view controller also has to conform to the UITableViewDelegate protocol.
#interface YourViewController : UIViewController <UITableViewDelegate, UITableViewDataSource>
As long as the table view has a data source and a delegate, it doesn't matter what kind of view controller it is on. All a UITableViewController really is is a UIViewController that already has a table view on it and is that table view's delegate and data source.
I know that this question have been asked so many times but unfortunately non of the solutions in those questions worked for me.
Here are some of the things I tried:
making sure that numberOfSectionsInTableView is not returning 0
making sure that numberOfRowsInSection is not returning 0.
insuring that reloadData is being called on the main thread by using performSelectorOnMainThread as shown below:
[self.tableView performSelectorOnMainThread:#selector(reloadData) withObject:nil waitUntilDone:NO]
setting the delegate in viewDidLoad, as shown below:
(void)viewDidLoad {
[super viewDidLoad];
// .....
self.tableView.dataSource = self;
self.tableView.delegate = self;
}
I'm creating an iOS app that keeps track of events. The app's main view is a UITableViewController (Calling it main list) that is embedded into a UINavigationController which is embedded into a UITabViewController. The user can create two objects a list or an event. When a new list is created and selected from the current UITableViewController, a new UITableViewController is pushed into the same UINavigationController.
Each list (UITableViewController) has an edit button that allows the user to delete the list.
Assuming that the user chooses to delete "list 3" that belongs to the main list, that is there are 3 view controllers pushed to the UINavigationController:
UITableViewController for the main list
UITableViewController for the selected list "list 3"
UITableViewController for the edit list view
when the delete button is tapped on, an alert is shown. If the user chooses to proceed the following code gets executed:
- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex {
// .....
//here I'm calling unwind which is going to pop the UITableViewController
//for the edit table view
[self performSegueWithIdentifier:#"unwindFromDelete" sender:nil];
//here I'm calling a method i wrote to pop the UITableViewController
//of the deleted list (in this example "list 3")
[self setNavigationControllerViewControllers];
// .....
}
- (IBAction)unwindFromEditListToList:(UIStoryboardSegue *)segue {
.....
}
- (void)setNavigationControllerViewControllers {
NSMutableArray *viewControllers = [[self.navigationController viewControllers] mutableCopy];
[viewControllers removeLastObject];
[self.navigationController setViewControllers:viewControllers];
}
After that code is executed, viewWillAppear for the main list UITableViewController is executed as shown below:
- (void)viewWillAppear:(BOOL)animated {
[super viewWillAppear:animated];
// ..... update the data
[self.tableView reloadData];
}
[self.tableView reloadData] is going to cause the following code to be executed:
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
// .....
return someValue; // Something greater than zero
}
- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section {
// .....
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
// .....
return someValue; //Something greater than zero
}
#pragma warning "Not getting called"
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
// .....
}
All the methods are executed but cellForRowAtIndexPath is not. The problem is gone if setNavigationControllerViewControllers mentioned above is not called. Not calling setNavigationControllerViewControllers will result in UITableViewController for "list 3" to show which is bad since "list 3" is no longer stored in the core data I'm using to store the data.
If you have any idea what to do, please let me know.
Thanks
numberOfSectionsInTableView must return at least 1.
See this link below.
You don't even need to override it if you're not using multiple sections.
If the height of table is dynamic. Make sure the table is in a view, visible and height is
atleast 1px when reload is called.
I put an answer on this because I've been browsing for a solution for sometime and this question is the closest to the one I was asking myself...
It turns out that I was using auto-layout with visual format.
Seems that UITableView and NSLayoutContraint don't play well together. As soon as I commented the method which apply constraints, the cellForRowAtIndexPath was called and the tableview displayed...
Please put debug point on this,
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
method and log someValue value may it return 0 that's why cellForRowAtIndexPath method not called.
Thanks.
Don't know who down voted Avalerion answer, but his statement is important too.
I had same problem, delegate method cellForRowAtIndexPath was not called though the following conditions were matched:
Delegate and Datasource was set
numberOfSectionsInTableView method was returning 1
numberOfRowsInSection returned correct number and data was available.
Reason:
I didn't set height constraint for the table, so it had no height, thus app didn't call cellForRowAtIndexPath even though it called eg numberOfRowsInSection.
The first time the view controller is pushed (from the previous view controller) all the delegate methods are called (inside a navigation controller).
When pressing back to return to the previous view controller , and then pushing it again (for the second time)
cellForRowAtIndexPath isn't called but numberOfRowsInSection and numberOfSectionsInTableView are called.
The reloadData is called within
-(void)viewWillAppear:(BOOL)animated
{
[self.tableView reloadData];
}
and I have tried in
-(void)viewDidAppear:(BOOL)animated
{
[self.tableView reloadData];
}
and it doesn't help.
Edit
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
return 1; // called
}
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
return 3; // called
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
// relevant code for cell - THIS METHOD IS NOT CALLED SECOND TIME
}
If you don't find any valid reason as explained above I will highlight
another mistake one can make is (as I once did).
The steps to note are
1) initialise your custom table view as first step
2) set the delegate and datasource before you add the tableView to you view.
If one has done these steps mistakenly after adding to the tableview to your self.view object, then it would be a silent way to make yourself struggle.Correct order is as under:
self.myTableView = [[UITableView alloc] initWithFrame:CGRectMake(0, 0, myViewwidth, 120) style:UITableViewStylePlain];
self.myTableView.tag = MY_TABLEVIEW_TAG;
self.myTableView.delegate = self;
self.myTableView.dataSource = self;
[self.view addSubview:self.myTableView];
This always happens when you define your underlying data source (array or Dictionary) as weak, the first time it gets pushed, the data is there, when deallocated, it will release and you lose control over it.
Double check the weak/strong condition and optionally set the data source before pushing again.
Please check if you have set/connected Delegate and Datasource to the File's Owner.
And check the array count of your model, if it contains value of not?
NSLog in the numberOfRowsInSection method and check it by using breakpoints and step over.
I try to display objects of an array in a tableview.
This is a single screen app, I'm using storyboard.
When running - the tableview appears as an empty grid. the data of the objects is not displayed. what may cause this?
Having 2 required methods numberOfRowsInSection and cellForRowAtIndexPath I suspect the last one.
The .h file contains this row:
#interface MYViewController : UIViewController <UITableViewDataSource, UITableViewDelegate>
I set the delegate & datasource via the code as you suggested. still empty grid.
This is my implementation:
-(NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section { return [listRecipes.recipeArray count]; }
-(UITableViewCell )tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { static NSString cellIdentifier = #"ListCellIdentifier"; MYCustomListCell* listCell = [tableView dequeueReusableCellWithIdentifier:cellIdentifier]; NSString* dataString = listRecipes.recipeArray[indexPath.row]; listCell.listName.text = dataString; listCell.imageView.image = [UIImage imageNamed:dataString]; return listCell; }
I try to display data from an array in MVC .
If the array is local - the data is displayed
Can you please advise what to do?
Thank you in advanced.
Always remember to hook up your table's delegate and datasources.
Being a UIElement on a UIViewController that conforms to these two protocols is not enough for Xcode to assume that that UIViewController should be the delegate and/or datasource for the table.
Right click on your tableview, drag from delegate & datasource to your UIViewController.
You can also set these programmatically via:
self.table.datasource = self;
self.table.delegate = self;
And if you're still having trouble after this, you'll have to show us how you're implementing the datasource protocol methods.
Check if your initialisation of tableview delegate and datasource would be before the recipeArray is initialised. In this case you will have to tableView.reload() after the items are added to recipeArray .
I have a UIViewController which has the following implementation for the didSelectItemAtIndexPath
#interface
id section1Item
NSMutableArray *section2Items
NSMutableArray *section3Items
#end
#implementation
- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath {
if (indexPath.section == 0) {
;
} else if (indexPath.section == 1) {
self.section1Item = [self.section2Items objectAtIndex:indexPath.row];
} else { // indexPath.section == 2
id newSection2Item = [self.section3Items objectAtIndex:indexPath.row];
[self.section2Items addObject:newSection2Item];
[self.section3Items removeObject:newSection2Item];
}
[collectionView reloadData];
}
#end
The idea behind the code is that my collectionView has a static number of sections, and taping on an item in section 3 moves the item to section 2, and tapping on an item in section 2 makes it an item in section 1.
However once I make the changes to my dataStructure (section1Item, section2Items and section3Items), and call reloadData, all my UICollectionView cells disappear. A few symptoms of the issue
After the reloadData call, non of my dataSource methods get recalled. I tried putting a breakpoint in my implementation of numberOfSectionsInCollectionView and collectionView:numberOfItemsInSection but they don't get hit.
I tried debugging using RevealApp, and I found out that after reloadData call, all my UICollectionViewCell's have their hidden property set to "YES", even though I don't have any code in my code base calling .hidden = YES;
I also tried overriding UICollectionViewCell#setHidden to detect what (if any) part of the UIKit framework calls it, and again there was no breakpoint triggers.
Tools details: I'm working with XCode5-DP6 on iOS7 simulator.
UPDATE: My UICollectionView shows all the cells correctly on first render.
Ok peeps, so I was able to figure out the issue. The delegate (self) was a subclass of UIViewController. In the init, I was assigning self.view = viewFromStoryBoard where viewFromStoryBoard was passed in by the caller and which was setup in a storyboard.
Since I was not really using any of the facilities offered by subclass UIViewController, I decided to switch to subclassing NSObject and manually retaining the pointer to the UICollectionView.
This fixed my problem. However I'm not a 100% on the exact nature of the issue. I'm guessing somehow overriding a UIViewController's view isn't all that it seems.
There are lots of bugs with iOS 7 and UICollectionView... In my case reloadData doesn't work correctly, it works with delay.