I've got a button in a custom Cell for a TableView which is supposed to open the camera for taking pictures.
I thought of two ways but can't get them working.
First one is to open an instance of UIImagePickerController from within the cell. Well, it seems like I can't call
[self presentViewController...];
from within the cell. Is this right?
Because of this "result" I thought of putting the method which opens up the UIImagePickerController inside the TableViewController and then call this method from within the cell (where the button is located) by something like
[super openCamera];
Or making the TableViewController the delegate of the cell to enable it to call the method.
Are these ideas going in the right direction? What would you recommend? Thank you very much!
Ok, I figured something out but I'm still wondering if it can be done easier.
Here is the solution I found:
In the custom cell I added
#property (nonatomic, assign) id adminController;
Then in the tableViewController I customized the following method to use the custom cell I created and set the tableViewController als "admin"
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"cell";
CreateCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];
// Configure the cell...
cell.adminController = self;
return cell;
}
So I could finally call
[self.adminController performSelector:#selector(openCamera)];
This is an old question but I'd like to have my old questions answered too so... Yes, there is an easier way using blocks:
First, declare a public method in your UITableViewCell interface:
#interface YourCell : UITableViewCell
#property (weak, nonatomic) IBOutlet UIButton *button;
- (void)setDidTapButtonBlock:(void (^)(id sender))didTapButtonBlock;
#end
In the UITableViewCell subclass implementation file declare a private property with a copy attribute.
#import "YourCell.h"
#interface YourCell ()
#property (copy, nonatomic) void (^buttonTappedBlock)(id sender);
#end
Add the target and action of the UIControl in the UITableViewCell constructor and implement the selector method
- (void)awakeFromNib {
[super awakeFromNib];
[self.button addTarget:self
action:#selector(didTapButton:)
forControlEvents:UIControlEventTouchUpInside];
}
- (void)didTapButton:(id)sender {
if (buttonTappedBlock) {
buttonTappedBlock(sender);
}
}
Finally implement the block code in the tableView:cellForRowAtIndexPath: method in the controller
- (UITableViewCell *)tableView:(UITableView *)tableView
cellForRowAtIndexPath:(NSIndexPath *)indexPath {
YourCell *cell = (YourCell *)[tableView dequeueReusableCellWithIdentifier:CellIdentifier
forIndexPath:indexPath];
[cell buttonTappedBlock:^(id sender) {
NSLog(#"%#", item[#"title"]);
}];
return cell;
}
For further information in blocks, you can read Working With Blocks
Related
I have UITableView with custom cells. On cell I have a buttons, and a method in my viewController (which contains UITableView)
My button click realisation is inside my myCustomCell class.
And the question is - What is the simplest way to call viewController method from myCustomCell?
I thought about delegates and NSNotificationCenter. But maybe there is another way.
EDIT
Put following lines in your myCustomCell.h
#protocol ButtonTapDelegate
- (void) buttonDidTap:(UIButton*) button;
#end
#property (nonatomic, weak) NSObject<ButtonTapDelegate> *vs_delegate;
-(void) buttonIsPressed;
in your myCustomCell.m
#synthesize vs_delegate;
-(void) buttonIsPressed:(UIButton*)button {
if([delegate conformsToProtocol:#protocol(ButtonTapDelegate)] && [delegate respondsToSelector:#selector(buttonDidTap:)]) {
[vs_delegate buttonDidTap:button];
}
}
In your viewController.h
myViewController : UIViewController <ButtonTapDelegate>
In your viewController.m, inside Method
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
[cell set.Vs_delegate:self];
[cell.button setTag:indexPath.row];
[cell.button addTarget:self action:#selector(buttonIsPressed) forControlEvents:UIControlEventTouchUpInside];
[cell.button buttonIsPressed:indexPath.row];
Put following method inside ViewController.m
- (void) buttonDidTap:(UIButton*) button {
// You have index, by Button's tag.
}
Most efficient and clean way to do this using blocks.
Declare a block property in your cell either TableViewCell or CollectionViewCell.
#property (nonatomic, copy) void(^buttonClickedAtIndexPath)(NSIndexPath *indexPath);
Declare button's action in Cell itself and Call above block in button click event.
-(IBAction)buttonClicked:(id)sender {
// get indexPath here, which will be indexPath of cell.
// you need to set button's tag as indexPath.row
if(self.buttonClickedAtIndexPath) {
self.buttonClickedAtIndexPath (indexPath);
}
}
In your ViewController
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
TableViewCell *cell = // configure cell here.
cell.button.tag = indexPath.row;
cell.buttonClickedAtIndexPath = ^(NSIndexPath *indexPath){
// you can do anything here.
// Call any method using self OR
// perform segue
}
}
If you've CollectionView inside TableViewCell then same things applies.
Make a class MyCollectionViewCell subclassing UICollectionViewCell.
Declare block property in MyCollectionViewCell.
Handle all the events in MyCollectionViewCell (including display data, delegate, datasource for collectionView).
Call a block from MyCollectionViewCell on button click.
Declare a property of MyCollectionViewCell in your TableViewCell.
In your controller's cellForRowAtIndexPath do something like this.
============================================================
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
TableViewCell *cell = // configure cell here.
cell.mycollectionView.buttonClickedAtIndexPath = ^(NSIndexPath *indexPath){
// you can do anything here.
// Call any method using self OR
// perform segue
}
}
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..
Is there anyway to control UIButton state (enable/disable button) in UITableViewCell. My problem is my UIButton in cell is made in storyboard using viewWithTag. I've been spending quite a lot of time to sort it out but no luck. People mostly sort out the problem by programmatically assigning the tag for the button with cell indexPath.
I'm aware of that the table will reuse the cell, but I just want to ask if there is another hacky way to sort out my issue. If it is impossible, I might have to create the button programmatically.
You could loop through all the subviews of the cell and check if they are a UIButton using isMemberOfClass to get your button. If you have multiple buttons you could then check the text of the button or some other property that uniquely identifies it. That would be a hacky way to do it.
You have to make a custom cell like that:
CustomCell.h
#protocol CustomCellDelegate <NSObject>
- (void)buttonPressed:(UIButton *)sender;
#end
#import <UIKit/UIKit.h>
#interface CustomCell : UITableViewCell
#property (weak, nonatomic) id<CustomCellDelegate> delegate;
#property (weak, nonatomic) IBOutlet UIButton *button;
- (IBAction)buttonPressed:(UIButton *)sender;
#end
CustomCell.m
#import "CustomCell.h"
#implementation CustomCell
- (id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self) {
// Initialization code
}
return self;
}
-(void)prepareForReuse{
self.button.enable = YES;
}
- (IBAction)buttonPressed:(UIButton *)sender{
[self.delegate buttonPressed:sender];
}
#end
after in IB you add a new UITableViewCell at your UITableView and the class of it with you new custom cell set the Identify ID like "CustomCell" add your Button to your custom cell and connect the Outlet, then you modify you tableView:cellForRowAtIndexPath: like that:
-(UITableViewCell*)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier=#"CustomCell";
CustomCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
cell.delegate = self;
return cell;
}
- (void)buttonPressed:(UIButton *)sender{
sender.enable = NO;
}
Also you have to add the CustomCellDelegate in your controller's heater file
One simple way would be to keep a NSMutableArray variable in your viewcontroller and with that keep track of what cells button is disabled/enabled. And use the UITableViewDataDelegate method:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
to set the buttons state each time it gets displayed. And UITableViewDelegate method:
– tableView:(UITableView *)tableView didEndDisplayingCell:(UITableViewCell *)tableViewCell forRowAtIndexPath:(NSIndexPath *)indexPath
to write to the array. Indexing with indexPath.
I'm figuring out the right mechanism to pass data from UITableViewCells to a UIableViewController (or UIViewController).
Searching within stackoverflow I found different ways to do this and finally I found a mechanism that works well but I don't know if it could be a valid approach.
This is the scenario. First, I created a custom cell (associated with a xib interface), named DataTableViewCell, that extends UITableViewCell. This cell has some outlet to display (and modify) data and an addictional property called index like the following:
#property (nonatomic, copy) NSIndexPath* index;
This property is refreshed inside the method cellForRowAtIndexPath method within the UITableViewController:
- (UITableViewCell *)tableView:(UITableView *)tv cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
DataTableViewCell *cell = (DataTableViewCell*)[tv dequeueReusableCellWithIdentifier:kCellTableIdentifier];
if (cell == nil)
{
[[NSBundle mainBundle] loadNibNamed:#"DataTableViewCell" owner:self options:nil];
cell = (DataTableViewCell*)self.dataTableViewCellOutlet;
}
// configure the cell with data
// do stuff here...
// configure the cell with the current indexPath
cell.index = indexPath;
return cell;
}
Since it is possible to change values within a cell, I had the need to pass data to the UITableViewController for updating the model. To do that I decided to use a delegate mechanism. So, I created a protocol with a method like the following:
- (void)updateData:(DataItem*)dataItem atIndexPath:(NSIndexPath*)index;
The UITableViewController implements that protocol. In this way, within the cell (against to some events), I can call that method and update the model in the correct way.
Having said this, I have some questions to ask:
Is this a right mechanism to pass data from a cell to a controller?
Is it correct to using an index property like the one use in the cell?
Is it the same using retain policy instead of copy policy. What could be the difference?
Since the solution I found could be very scheming, is it possible to use block insteads?
About blocks, I thought this way:
Within the cell create a property block like the following:
#property (nonatomic, copy) void (^updateModelOnEvent)(DataItem* dataItem);
Then inside the method cellForRowAtIndexPath method within the UITableViewController assign that property to a block code like this (this code is at the same level of cell.index = indexPath;):
// configure the cell with the current indexPath
cell.updateModelOnEvent = ^(DataItem* dataItem) {
[self.model insertObject:dataItem atIndex:indexPath.row];
};
Could be a valid alternative? In this case, do I have to use copy or retain policy?
Thank you in advance.
Why not just use [UITableView indexPathForCell:] with a delegate?
MyViewController.h
#interface MyViewController : UITableViewController <MyTableViewCellDelegate>
#end
MyViewController.m
#implementation MyViewController
// methods...
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
NSString *reuseIdentifier = #"MyCell";
MyTableViewCell *cell = (id)[tableView dequeueReusableCellWithIdentifier:reuseIdentifier];
if (cell == nil)
cell = [[[MyTableViewCell alloc] initWithMyArgument:someArgument reuseIdentifier:reuseIdentifier] autorelease];
[cell setDelegate:self];
// update the cell with your data
return cell;
}
- (void)myDelegateMethodWithCell:(MyTableViewCell *)cell {
NSIndexPath *indexPath = [self.tableView indexPathForCell:cell];
// update model
}
#end
MyTableViewCell.h
#protocol MyTableViewCellDelegate;
#interface MyTableViewCell : UITableViewCell
#property (assign, nonatomic) id <MyTableViewCellDelegate> delegate;
- (id)initWithMyArgument:(id)someArgument reuseIdentifier:(NSString *)reuseIdentifier;
#end
#protocol MyTableViewCellDelegate <NSObject>
#optional
- (void)myDelegateMethodWithCell:(MyTableViewCell *)cell;
#end
MyTableViewCell.m
#implementation MyTableViewCell
#synthesize delegate = _delegate;
- (id)initWithMyArgument:(id)someArgument reuseIdentifier:(NSString *)reuseIdentifier {
self = [super initWithStyle:UITableViewCellStyleDefault reuseIdentifier:reuseIdentifier];
if (self) {
// custom setup
}
return self;
}
- (void)prepareForReuse {
[super prepareForReuse];
self.delegate = nil;
}
- (void)someActionHappened {
if ([self.delegate respondsToSelector:#selector(myDelegateMethodWithCell:)])
[self.delegate myDelegateMethodWithCell:self];
}
#end
To modify cells you should modify data model and reload table data. Nothing else.
Not necessary to have a indexPath for cell
In your case it is the same using retain or copy policy. Copy makes new objects with same state.