In my iPhone application, I am using a UITableView with custom table cells by subclassing UITableViewCell. Let's assume my custom cell class name as ItemTableViewCell. The relevant ItemTableViewCell.xib has a subview of UIView with the name of infoView.
I want that infoView identify single tap/touch it gets. If it is just a tap, I can do it by adding UITapGestureRecognizer using story board and having a action method for that. But what I need is while identify the tap/touch of infoView, I need to pass the relevant table row info to the target method/selector.
If I further explain the situation, UITableView consists of NSArray of UITableViewCell. That custom cell has a bottom bar with a subview called infoView. By tapping/touching that infoView it should call a method with the related NSArray element as parameter. By tap/touching the rest of the cell, it should call didSelectRowAtIndexPath method as normal.
I have found a solution. While I'm creating custom cells, I'm adding UITapGestureRecognizer to the relevant UIVIew (in my case it's infoView) like below.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(tappedOnInfoView:)];
[tap setNumberOfTouchesRequired:1];
[tap setNumberOfTapsRequired:1];
[cell.infoView addGestureRecognizer:tap];
[cell.infoView setUserInteractionEnabled:YES];
[cell.infoView setTag:realIndex];
As you can see from the last line, I'm passing the cell index rather than the cell data to the selector which will fire after identify tap gesture.
At the same time I'm maintaining an NSMutableArray to store data of the cell. As you can understand, there will be simultaneous NSArray elements for each cell index.
This is how my selector appears;
- (void)tappedOnInfoView:(UIGestureRecognizer *)sender {
By using below code you can get the index related to the tap guesture occured
sender.view.tag
Using follow code snippet I'm able to get the details of cell where I've store in a NSMutableArray
[myMutArray objectAtIndex:sender.view.tag];
Mission accomplished :)
Implement gesture action in Tableview SuperClass. Or You can use Custom delegate in UITableViewCell subclass. In UITableView Subclass declare a protocol.
#protocol customCellDelegate <NSObject>
#required
-(void)selectedCellInIndexPath : (NSIndexPath *)indexpath;
#end
Set this property in UITableView Subclass
#property (nonatomic, strong)NSIndexPath *indexpath;
#property (nonatomic, strong) id <customCellDelegate> delegate;
And then in Your UITableView Subclass gesture action add This lines
if(self.delegate){
[self.delegate selectedCellInIndexPath: self.indexpath];
}
And in your tableview datasource method
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath;
Implement this code
cell.delegate = (id)self;
cell.indexpath = indexPath;
And in Uitableview super class just implement this method
-(void)selectedCellInIndexPath : (NSIndexPath *)indexpath{
//display uiimagepickercontroller modally or anything else here
}
Related
How can I pass data from a cell by pressing a button in the same cell. Lets say I have a table with 3 cells row, each cell has a label with different value. What I need is when I press the button in cell 2 pass that value to another ViewController. Passing the data between controller is not problem when I press on the cell it's self, but my problem is when I press the specific button and hold the value of some string from that cell.
Thanks
You have to delegate button action to controller. You should research it yourself but I'm gonna give you short example.
Let's assume you have a UITableViewCell , and of course UITableView has its own delegate methods like
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
- (void)tableView:(UITableView *)tableView didDeselectRowAtIndexPath:(NSIndexPath *)indexPath
these are selection of a cell, but you want to control a button action.
So you have a button inside cell like this
UIButton *someButton = [[UIButton alloc] initWithFrame:CGRectMake(0,0, 50, 50)];
[someButton addTarget:self action:#selector(buttonClicked) forControlEvents:UIControlEventTouchUpInside];
[self addSubview:someButton];
this is in your cell class.
and .h of your cell you write delegation like this.
#protocol SomeProtocol <NSObject>
- (void) buttonPressedInCell:(NSString *) data;
#end
and your delegate property in .h
#property (nonatomic, strong) id<SomeProtocol> delegate;
and your cell.m
finally you can give delegate to your button action
- (void) buttonClicked {
[delegate buttonPressedInCell];
}
so after this you can delegate this object whenver you want, in your case you want to give it to your UITableView let's do it.
you have like a CustomTableViewCell
and your controller you must yourController<SomeProtocol>
and you have to delegate your cell like yourCell.delegate = self;
then implement your delegate method
- (void) buttonPressedInCell:(NSString *) data {
// do something like pushing new controller
//your data is in your controller now
}
Hope this helps you.
More information about delegation here
I have a custom uitableviewcell and subclassed, and it is containing a uitextfield and delegate is also set, now when return key on keyboard is pressed I want to try few things
perform a segue(but issue is I am in uitableviewcell subclass).
modally present another view controller(but issue is uitableviewcell
do not allow this).
I want to display uiactionsheet(but again limitation is
uitableviewcell).
If i get rootviewcontroller reference then rootviewcontroller's view itself not displayed or not the active view so any thing you do will not present on screen, active view is required.
You could use a block property on your cell that is fired whenever your custom button action occurs. Your cell's block property might look something like this:
#interface CustomTableViewCell : UITableViewCell
#property (nonatomic, copy) void (^customActionBlock)();
#end
Your cell would then invoke this block from the custom button action like this:
#implementation CustomTableViewCell
- (IBAction)buttonTapped:(id)sender {
if ( self.customActionBlock ) {
self.customActionBlock();
}
}
#end
Then finally, you set the block in -cellForRowAtIndexPath: back in your view controller (or wherever) like this:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
CustomTableViewCell * cell = [tableView dequeueReusableCellWithIdentifier:#"customCell" forIndexPath:indexPath];
cell.textLabel.text = [self.colors objectAtIndex:indexPath.row];
cell.customActionBlock = ^{
NSLog(#"Do the stuff!");
// present view controller modally
// present an action sheet
// etc....
};
return cell;
}
One word of caution, though. If you use blocks you run the risk of strongly referencing self and creating a memory leak. Blocks are fun and easy to use but you have to play by their rules. Here are some resources to help you get familiar with them:
Retain cycle on `self` with blocks
Reference to self inside block
http://aceontech.com/objc/ios/2014/01/10/weakify-a-more-elegant-solution-to-weakself.html
http://fuckingblocksyntax.com
You can attach action to your buttons even if they are in a tableView
[cell.button addTarget:self action:#selector(presentController:) forControlEvents:UIControlEventTouchUpInside];
presentController is referring to an IBAction
- (IBAction)presentController:(id)sender
{
//present
}
Implement button action in Tableview SuperClass.
Or You can use Custom delegate in UITableViewCell subclass. In UITableView Subclass declare a protocol.
#protocol customCellDelegate <NSObject>
#required
-(void)selectedButtonInIndexPath : (NSIndexPath *)indexpath;
#end
Set this property in UITableView Subclass
#property (nonatomic, strong)NSIndexPath *indexpath;
#property (nonatomic, strong) id <customCellDelegate> delegate;
And then in Your UITableView Subclass Button action add This lines
if(self.delegate){
[self.delegate selectedButtonInIndexPath: self.indexpath];
}
And in your tableview datasource method
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath;
Implement this code
cell.delegate = (id)self;
cell.indexpath = indexPath;
And in Uitableview super class just implement this method
-(void)selectedButtonInIndexPath : (NSIndexPath *)indexpath{
//display uiimagepickercontroller modally or anything else here
}
I have a segue from a view controller - with a enclosed tableview - to another view controller. I can segue from each cell in the first controller to the second with no problem. However, when I return to the first controller, the cell view is blank.
The dilemma is -- If I use this method:
- (BOOL)tableView:(UITableView *)tableView shouldHighlightRowAtIndexPath:(NSIndexPath *)indexPath {
return NO;
}
the cell is visible but segues do not work.
Does anyone know of an alternative method?
Thanks
You need to create custom table view cell(may be you already have one, then tweak it), lets call it MyTableViewCell. Then add UITapGestureRecognizer to handle tap events on cell's contentView. When tap occurs you can execute custom block, which you should setup for cell. In block you can perform desired segue. But enough word, lets see some code!
First, lets define MyTableViewCell
MyTableViewCell.h
typedef void (^MyTableViewCellTapBlock) ();
#interface MyTableViewCell : UITableViewCell
#property (nonatomic, strong) MyTableViewCellTapBlock tapBlock;
#end
MyTableViewCell.m
#interface MyTableViewCell ()
#property (nonatomic, strong) UITapGestureRecognizer *tapRecognizer;
#end
#implementation MyTableViewCell
- (void)awakeFromNib {
self.tapRecognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(handleTap:)];
[self.contentView addGestureRecognizer:self.tapRecognizer];
}
- (void)handleTap:(UITapGestureRecognizer *)recognizer {
NSLog(#"Tap logged");
if (self.tapBlock) {
self.tapBlock();
}
}
#end
Second, update your UITableViewDataSource
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
MyTableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:#"Cell" forIndexPath:indexPath];
__weak typeof(self) weakSelf = self;
cell.tapBlock = ^ {
[weakSelf performSegueWithIdentifier:#"showDetail" sender:weakSelf];
};
return cell;
}
Remarks
As you can see we have custom block that will be executed when user taps the cell. This block invokes performSegueWithIdentifier:, just do not forget to name your segue and change name in the sample.
Happy coding :)
Thanks for the efforts Keenie.. I will hold on to that code snippet and I know I'll use it.
This is embarrassing, but it turns out that all I needed to do, was on the return from the segue, to do [[self tableView] reloadData], and all was ok..
I don't know if this is considered to be an accepted Objective-C practice or not, so I'm open to other ideas. Here is the idea. I have a table that gets is cells from a custom UITableViewCell. Each of these cells presents an event that the user can attend. As such, I'd like for the user to be able to add them to their calendar directly from the table view.
To accomplish this, I put a button on each table cell - an "add to calendar button". What I am stuck on is how to wire an action from this button back to the UIViewController where the UITableView is a subview. The button is part of a UITableView class and doesn't have visibility to the UIViewController.
I've been trying to implement the delegate pattern suggested by Aaron below. I'm almost there, but something is still disconnected. Here is what I have:
New protocol EventDelegate.h
#protocol EventDelegate <NSObject>
- (void) addToCalendar : (NSString *) strDate;
#end
In MyTableCell.h, I have added this property:
#property (nonatomic, strong) id<EventDelegate> eventDelegate;
In MyTableCell.m, I have added this method:
- (IBAction)addToCalendar:(UIButton *)sender
{
NSLog(#"calling addToCalendar delegate %#", _dayAndTime.text);
[self.eventDelegate addToCalendar:_dayAndTime.text];
}
All is well to this point. When I click on the button that I added to the table cell, I get the output calling addToCalendar delegate Monday, January 13
Over in MyViewController.h, I changed it look like this:
#interface TrainingScheduleViewController : UIViewController <UITableViewDelegate, UITableViewDataSource, EventDelegate>
- (void) addToCalendar:(NSString *)strDate;
#end
And finally, in MyViewController.m I added the method body:
- (void) addToCalendar:(NSString *)strDate
{
NSLog(#"inside delegate");
NSLog(#"%#", strDate);
}
The part that I think might be the problem is where Aaron suggests adding this line of code:
[tableViewController setEventDelegate:self];
First, I'm not sure where to add this line. I put it in viewDidLoad. The compiler wouldn't let me type it verbatim, so the closest thing that I could find was this line:
[self.tableView setDelegate:self];
Maybe I need an additional outlet?
I have to be almost there, but I just don't see what I am still missing. Can anyone help me? Thanks!
Here is some example code that I pulled from my "cellForRowAtIndexPath" method. This is from a table that was built in IB and uses a prototype cell, but the idea is the same no matter how you implement. In this case, I use a tag to identify the button, then reference it when the cell is created:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:#"Cell" forIndexPath:indexPath];
UIButtonRed *actionButton = (UIButtonRed *)[cell.contentView viewWithTag:4];
[actionButton addTarget:self action:#selector(initializeReorder:) forControlEvents:UIControlEventTouchDown];
return cell;
}
The initializeReorder: method automatically receives (id)sender as a parameter. You can cast that to a table cell and inspect it to get the rest of your info:
- (void)initializeReorder:(id)sender
{
UIButtonRed *actionButton = (UIButtonRed*)sender;
UITableViewCell *cell = (UITableViewCell*)actionButton.superview.superview;
NSIndexPath* cellPath = [self.tableView indexPathForCell:cell];
...
}
Create a protocol for this.
I would define a protocol like this:
#protocol MyEventDelegate <NSObject>
- (void)addToCalendar:(Event*)event;
#end
And add a delegate property to both your UITableViewController class and your MyTableCell class:
#property (nonatomic, strong) id<MyEventDelegate> eventDelegate;
MyViewController should conform to this protocol and implement addToCalendar:
#interface MyViewController : UIViewController <MyEventDelegate>
When your MyViewController object sets up the UITableViewController, pass in a reference to itself:
[tableViewController setEventDelegate:self];
and when your UITableViewController creates each cell, pass it on:
[cell setEventDelegate:self.eventDelegate];
Now, when the IBAction is called in your cell, the cell can call the delegate method on MyViewController like so:
[self.eventDelegate addToCalendar:event];
I have a class like this:
#interface ExerciseLogDetails : UIViewController<UIActionSheetDelegate, UITableViewDelegate, UITableViewDataSource> {
where I am trying to display some elements followed by a UITextView. The UITextView element is created on Interface Builder. When executing this code:
- (void)viewDidLoad {
self.tableView = [[UITableView alloc] initWithFrame:self.view.bounds style:UITableViewStylePlain];
tableView.dataSource = self;
tableView.delegate = self;
[self.view addSubview:self.tableView];
}
a table shows, but not the one I configured in Interface Builder. It is completely blank and unformatted. How can I access my table and populate it progrmmatically with data?
Thank you!
Several of the tips on this thread helped me create this. I am going to offer some more complete code files in order to help others as well:
Step 1. Drag your UITableView onto your View Controller either in Storyboards or XIBs. In my example I am using a story board.
Step 2: Open your ViewController (in my case its just DefaultViewController) and add the two delegates for the UITableView: UITableViewDelegate and UITableViewDataSource. Also add a simple data source for population and the UITableView IBOutlet.
DefaultViewController.h
#import <UIKit/UIKit.h>
#interface DetailViewController : UIViewController <UITableViewDelegate, UITableViewDataSource>
#property (strong, nonatomic) IBOutlet UITableView *tableView;
#property (strong, nonatomic) NSMutableArray *newsArray;
#end
Step 3: Open your implementation file (DefaultViewController.m) and add the following:
#import "DetailViewController.h"
#interface DetailViewController ()
- (void)configureView;
#end
#implementation DetailViewController
#synthesize newsArray;
#synthesize tableView;
#pragma mark - Managing the detail item
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
[self configureView];
}
- (void)configureView
{
// Update the user interface for the detail item.
self.newsArray = [[NSMutableArray alloc] initWithObjects:#"Hello World",#"Goodbye World", nil];
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
#pragma mark UITableViewDelegate
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
// typically you need know which item the user has selected.
// this method allows you to keep track of the selection
}
- (UITableViewCellEditingStyle)tableView:(UITableView *)tableView
editingStyleForRowAtIndexPath:(NSIndexPath *)indexPath
{
return UITableViewCellEditingStyleDelete;
}
// This will tell your UITableView how many rows you wish to have in each section.
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
return [self.newsArray count];
}
// This will tell your UITableView what data to put in which cells in your table.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifer = #"CellIdentifier";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifer];
// Using a cell identifier will allow your app to reuse cells as they come and go from the screen.
if (cell == nil)
{
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifer];
}
// Deciding which data to put into this particular cell.
// If it the first row, the data input will be "Data1" from the array.
NSUInteger row = [indexPath row];
cell.textLabel.text = [self.newsArray objectAtIndex:row];
return cell;
}
#end
Step 4: Goto your Storyboards or XIB and select your UITableView and drag the datasource and delegate outlets onto your DefaultViewController to wire them up. Also you will need to wire up the Referencing Outlet for the UITableView to your IBOutlet tableView object you created in your header file.
Once this is finished you should be able to run it and the sample data will be in place.
I hope this along with the other tips on this thread will help others setup a UITableView from scratch on a ViewController.
If you configured a tableView in IB you shouldn't also create one programmatically, you should create #property (nonatomic, retain) IBOutlet UITableView *tableView; and connect it to the tableView you configured in IB.
Try to set a breakpoint in the tableView's
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
delegate method to see if this method get called.
From Apple UITableView docs:
A UITableView object must have an object that acts as a data source
and an object that acts as a delegate; typically these objects are
either the application delegate or, more frequently, a custom
UITableViewController object. The data source must adopt the
UITableViewDataSource protocol and the delegate must adopt the
UITableViewDelegate protocol. The data source provides information
that UITableView needs to construct tables and manages the data model
when rows of a table are inserted, deleted, or reordered. The delegate
provides the cells used by tables and performs other tasks, such as
managing accessory views and selections.
As u can see if u don't set a dataSource to your tableView, the tableView will not know how and what to display, so nothing will happen.
You can set one by calling tableView.dataSource = self; or in IB drag from your tableView to the file's owner (that is your viewController that must implement the UITableViewDataSource Protocol)
There are two methods in the UITableViewDataSource protocol that your dataSource must implement:
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
and
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath: (NSIndexPath *)indexPath
If u won't implement those methods u will get a compiler warnings.
You can have more control on how the tableView will look if you implement the UITableViewDelegate protocol - like row/header/footer height, selections and more...
From Apple UITableView docs:
UITableView overrides the layoutSubviews method of UIView so that it
calls reloadData only when you create a new instance of UITableView or
when you assign a new data source. Reloading the table view clears
current state, including the current selection. However, if you
explicitly call reloadData, it clears this state and any subsequent
direct or indirect call to layoutSubviews does not trigger a reload.
ReloadData get called when the tableView is created or when you assign a new dataSource (or when you explicitly call it of course..).
This is when the tableView needs to know what to display (how many sections?, how many rows?, and which cell to display?) - So this is when numberOfRowsInSextion method called.
Like Eyal said, you shouldn't create a UITableView programmatically and in the Interface Builder. Instead, it is much easier to just create one in Interface Builder and assigns it's delegate and datasource properties to File's Owner in IB.
Once you've done this, you don't need to create one programmatically and there's no need for a #property for the tableview.
Instead, you could have your UIViewController's class files look like this:
// YourViewController.h
#import <UIKit/UIKit.h>
#interface YourViewController : UIViewController <UITableViewDelegate, UITableViewDataSource>
#property (strong, nonatomic) NSArray *yourData;
#end
Where the NSArray will contain your data that you will enter into the table programmatically. You may use other data classes too like an NSDictionary depending on what data you have and how you want it to sit in the table.
// YourViewController.m
#import "YourViewController.h"
#implementation YourViewController
#synthesize yourData;
- (void)viewDidLoad
{
[super viewDidLoad];
// Here you are creating some data to go in your table by inputting it as an array.
// I just used some basic strings as an example.
NSArray *array = [[NSArray alloc] initWithObjects:#"Data1", #"Data2", #"Data3", nil];
// Copying the array you just created to your data array for use in your table.
self.yourData = array;
}
- (void)viewDidUnload
{
[super viewDidUnload];
self.yourData = nil;
}
#pragma mark Table View Data Source Methods
// This will tell your UITableView how many rows you wish to have in each section.
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
return [self.yourData count];
}
// This will tell your UITableView what data to put in which cells in your table.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifer = #"CellIdentifier";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifer];
// Using a cell identifier will allow your app to reuse cells as they come and go from the screen.
if (cell == nil) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifer];
}
// Deciding which data to put into this particular cell.
// If it the first row, the data input will be "Data1" from the array.
NSUInteger row = [indexPath row];
cell.textLabel.text = [yourData objectAtIndex:row];
return cell;
}
#end
This should just create a simple UITableView with three entries of data that you have entered programmatically.
If you have any problems or questions just post a comment. :)
Hope this helps.