How to achieve "dequeueReusableCellWithIdentifier" - ios

sorry, I wanna to know that apple's underlying code implementation

In storyboards you can set identifier of each of the cells you put inside the table view by setting any text to Identifier field:
The text in your code must be exactly the same, case sensitive to use it.
There are also ways of doing this programmatically to register a cell on table view before using it (setting it in viewDidLoad should be enough).
- (void)viewDidLoad {
[super viewDidLoad];
[self.tableView registerClass:[MyTableViewCell class] forCellReuseIdentifier:#"MyTableViewCellIdentifier"];
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
MyTableViewCell *myCell = [tableView dequeueReusableCellWithIdentifier:#"MyTableViewCellIdentifier"];
return myCell;
}

Related

TableView in a TableViewCell

I want to put a tableview into a tableview cell. I like the formatted look it gives. I'm hoping to put in a few fields, for like name, email, etc. What am I missing to be able to make this work? Currently I can not set "ProfileCell" as the tableview class.
In my .h file of the profile cell I added:
#interface ProfileCell : UITableViewCell <UITableViewDataSource,UITableViewDelegate>
and in my .m file I added some basic methods for the tableview:
#import "ProfileCell.h"
#implementation ProfileCell
- (void)awakeFromNib {
// Initialization code
}
- (void)setSelected:(BOOL)selected animated:(BOOL)animated {
[super setSelected:selected animated:animated];
// Configure the view for the selected state
}
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
return 1;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
// Number of rows is the number of time zones in the region for the specified section.
return 1;
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
NSLog(#"Doing this");
static NSString *MyIdentifier = #"MyReuseIdentifier";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:MyIdentifier];
return cell;
}
#end
EDIT:
I have seperated the code for the cellview tableview into it's own files, and linked tableview to this class, however it does not fire when viewed:
#interface ProfileBasicDetails : UITableView <UITableViewDataSource,UITableViewDelegate>
Per comments below
This is what my page should look like when said and done. It's so users can enter in their details, while looking nice and formatted, but not ghetto looking.
I'm assuming you've embedded the UITableView into the cell?
You should wire the tableview to an outlet in the cell. Then set the delegate on the tableview in your awakeFromNib method.
*As vikingosegundo mentioned in the comments, this is potentially a pretty fragile approach.

Hiding checkmarks in UITableView multiple selection during Edit Mode

I've got a UITableView which is automatically set up for multiple selection in Edit Mode using the following lines in viewDidLoad:
self.tableView.allowsMultipleSelectionDuringEditing = YES;
[self setEditing:YES animated:YES];
However, I'd like to indicate that a row was selected by changing its background color, rather than by the checkmarks which automatically appear along the left of each row. (For example, the ones that appear when editing the email list in the Mail app, or being discussed in this SO question.) I've got it working for the most part, except that I can't get those checkboxes, which are automatically created as part of putting the UITableView into Edit Mode, to go away.
Below is the code I'm working with:
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView{
return 1;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{
return _Hierachy.cellCount;
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
UITableViewCell *testCell = [tableView dequeueReusableCellWithIdentifier:#"cell"];
if(testCell == nil) {
testCell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:#"cell"];
}
[[testCell textLabel] setText:#"Test Cell"];
return testCell;
}
Those are the only UITableView methods I've got so far, so everything else should be default behavior.
Does anyone know how to hide those checkmarks along the left, in Edit Mode? I've seen many questions about checkmarks in the accessory portion of the cell, but as I understand it, this is a different thing. I've also seen people talk about the tableView:didSelectRowAtIndexPath: method, but these checkmarks are created when the table enters Edit mode and dismissed when the user taps "Done," so that method doesn't seem related.
The closest I've come is finding this method:
- (BOOL)tableView:(UITableView *)tableView shouldIndentWhileEditingRowAtIndexPath:(NSIndexPath *)indexPath{
return NO;
}
But that just prevents the cell's content from indenting to make room for the checkmarks. The checkmarks still appear.
Surely there's a way to hide those checkmarks, and still allow multiple selection in Edit Mode? Or are those checkmarks seriously mandatory behavior for a UITableView in Edit Mode with Multiple Selection enabled?
EDIT: I am (reluctantly) open to answers that are somewhat hack-y, like moving the frame of the checkmarks until it's off the screen. This app is for internal use, and won't need to be approved for the App Store. But given that the checkmarks are created automatically when the UITableView moves into Edit Mode, I don't even know how to get them as objects to alter. Any help would be appreciated!
You'll have to subclass your UITableViewCell and override the (void)setEditing:animated: method like this:
#import "MyCustomCell.h"
#implementation MyCustomCell
- (id)initWithStyle:(UITableViewCellStyle)style reuseIdentifier:(NSString *)reuseIdentifier
{
self = [super initWithStyle:style reuseIdentifier:reuseIdentifier];
if (self) {
// Initialization code
}
return self;
}
- (void)setSelected:(BOOL)selected animated:(BOOL)animated
{
[super setSelected:selected animated:animated];
// Configure the view for the selected state
}
- (void)setSelectedBackgroundView:(UIView *)selectedBackgroundView
{
//Cell Selected Color: CLEAR
[super setSelectedBackgroundView:selectedBackgroundView];
}
- (void)setEditing:(BOOL)editing animated:(BOOL)animated
{
//Cell Edit Mode NO Indent & Selected Color: CLEAR
[super setEditing:NO animated:animated];
[self setNeedsLayout];
}
#end
After you do that, go to Inteface Builder and make your cell part of the class MyCustomCell.
After you make your cell part of MyCustomCell class in IB, import MyCustomCell.h in your UITableViewController and modify the following in your code:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
MyCustomCell *testCell = [tableView dequeueReusableCellWithIdentifier:#"cell"];
if(testCell == nil) {
testCell = [[MyCustomCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:#"cell"];
}
[[testCell textLabel] setText:#"Test Cell"];
return testCell;
}
UPDATE:
You could also do the following in your TableView's tableView:editingStyleForRowAtIndexPath:
- (UITableViewCellEditingStyle)tableView:(UITableView *)tableView editingStyleForRowAtIndexPath:(NSIndexPath *)indexPath
{
return UITableViewCellEditingStyleNone;
}
But you will get your cell indented. To remove that indent you'll have to subclass the Cell.
You should be good to go after doing this! I've just tested it and it works the way you want it!
Here is the most simple solution for multiple selection with no checkmarks:
- (BOOL)tableView:(UITableView*)tableView canEditRowAtIndexPath:(NSIndexPath*)indexPath {
return NO;
}
This will cause the cells to be selected using the default selection style (gray or using your custom selection background), and no checkmarks will appear.
A word on whatever solution you pick. Users expect a consistent experience across multiple applications, and these checkmarks are part of this consistency. Make sure to have a good reason to change a normal OS look and feel.
here is how to achieve:
swipe to delete works
you don't see the checkbox, delete item or anything else on the left of the cell when in editing mode
Cell indentation still works normally (you can turn this off if you want)
(bonus) Support multiple selection
so - in your UITableViewDelegate
- (BOOL)tableView:(UITableView *)tableView canEditRowAtIndexPath:(NSIndexPath *)indexPath
{
return YES;
}
- (UITableViewCellEditingStyle)tableView:(UITableView *)tableView editingStyleForRowAtIndexPath:(NSIndexPath *)indexPath
{
if (self.isEditing)
{
return UITableViewCellEditingStyleNone;
}
else
{
return UITableViewCellEditingStyleDelete;
}
}
- (void)tableView:(UITableView *)aTableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath
{
(do stuff)
}
you also need to configure your UITableView
self.table.allowsMultipleSelectionDuringEditing=NO;
now if you actually do want multiple selection;
self.table.allowsSelectionDuringEditing=YES;
then manage the selected cells yourself.
I put a custom checkbox in my UITableViewCell subclass, and I also change the value in response to
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
The questioner wants to indicate selection with the background colour - that part should be straightforward.

Custom UITableViewCell in storyboard won't load

I'm facing a strange problem. I have an iOS 7.1 storyboard app with a UITableViewController using Xcode 5. I created a subclass of UITableViewCell and set it as the class for the cell from the IB and also added a cell identifier. The style is set to Custom as well. I haven't made any modifications to this subclass yet though. It has only the template code you get when you create a new class.
In the table view controller I have this code. Just setting the data source and the delegate methods.
#import "TableViewController.h"
#import "TextFieldTableViewCell.h"
#interface TableViewController ()
#end
#implementation TableViewController
- (void)viewDidLoad
{
[super viewDidLoad];
}
#pragma mark - Table view data source
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
return 1;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
return 10;
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"cell";
TextFieldTableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
cell.textLabel.text = #"hello world";
return cell;
}
In the cellForRowAtIndexPath, I simply set a value to the textLabel property of the cell. Even that doesn't get shown up. I double checked the identifier, style and everything bit they are all set.
I have no idea why this isn't working. I also checked out a few online tutorials on this subject matter like this one but I have everything as they've described.
Can anyone please tell me if I'm missing anything?
I've uploaded a test project to my Dropbox here if you want to take a quick look at it.
Found it! You've overridden the layoutSubviews of TextFieldTableViewCell class, and wrote nothing inside of it.
Just remove the layoutSubviews (for now) and it will work.
Update: A better solution;
- (void) layoutSubviews
{
[super layoutSubviews];
}

error when registering a custom uitableviewcell

"invalid nib registered for identifier (myGoal) - nib must contain exactly one top level object which must be a UITableViewCell instance"
Thats the exception I keep on getting. I am using both, storyboard and XIB.
In my storyboard, I have a tableview inside of a navigation view. The tableview is set to dynamic prototypes and the number of prototype cells is zero. The reason is because I wanted to add a custom cell programmatically.
The first time I added the cells programmatically, I was using one of the generic cell styles. At it would work!
- (void)viewDidLoad
{
[super viewDidLoad];
[self.tableView registerClass:[UITableViewCell class] forCellReuseIdentifier:#"myGoal"];
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:#"myGoal"
forIndexPath:indexPath];
//do stuff with cell
}
It would let me have a tableview with the default cell style, which has one label.
Next I wanted to customize my cell so that it would have multiple label and a few extra buttons. Normally, I'd do it in a storyboard interface builder, but this time I need to do it programatically.
So I created a custom tableviewcell class along with its Xib counterpart. In the Xib I designed it how I wanted. The problem is in getting this cell to show up in the tableview.
Does it matter that the tableview is in a storyboard and the tableviewcell is in a xib?
In order to register the custom nib, I did almost the same thing as above, yet it crashes:
- (void)viewDidLoad
{
[super viewDidLoad];
UINib *dhCustomNib = [UINib nibWithNibName:#"DHTableViewCell" bundle:nil];
[self.tableView registerNib:dhCustomNib forCellReuseIdentifier:#"myGoal"];
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
DHTableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:#"myGoal"
forIndexPath:indexPath]; //It crashes at this point
//do stuff with cell
}
What am I missing?
You need to set the top level object as the DHTableViewCell subclass not the file's owner.

Fails to call delegate/datasource methods in UITableView implementation

I have created .h and .m files for UITableView called mainTableViewgm.h and mainTableViewgm.m resp. and I am calling -initWithFrame: method from my main view controller to this mainTableViewgm.m implementation file
[[mainTableViewgm alloc]initWithFrame:tableViewOne.frame]
Note that this tableview is in my main view controller. But I have created separate files for the tableView and have also set the custom class to mainTableViewgm in storyboard.
the -initWithFrame: methods appears as follows
- (id)initWithFrame:(CGRect)frame
{
//NSLog(#"kource data");
self = [super initWithFrame:frame];
if (self)
{
[self setDelegate:self];
[self setDataSource:self];
[self tableView:self cellForRowAtIndexPath:0];
[self tableView:self numberOfRowsInSection:1];
// Initialization code
}
return self;
}
-(NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
NSLog(#"kource data");
return 1;
}
-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
NSLog(#"kource data2");
UITableViewCell*cellOne =[[UITableViewCell alloc]init];
cellOne.detailTextLabel.text=#"text did appear";
return cellOne;
}
the -initWithFrame: is being called fine along with the 'if (self)' block in this method. But the problem is numberOfRowsInSection: and cellForRowAtIndexPath: are not being automatically called here . kource data/kource data2 never appear in log. What do I do to load the table? Are the delegate/datasource being set incorrectly?
I must mention that I have also set the UITableViewDelegate and UITableviewDataSource protocols:
#interface mainTableViewgm : UITableView <UITableViewDelegate,UITableViewDataSource>
#end
Help will be much appreciated. Thank you.
Your tableview is not loaded when the controller is initializing, so you cannot do that in the init methods. You have to move your code to the viewDidLoad method.
Also you are not setting the delegate and datasource on the tableview object (probably a type, you are setting them on the view controller). It should look like this:
- (void)viewDidLoad:(BOOL)animated {
[super viewDidLoad:animated];
[self.tableView setDelegate:self];
[self.tableView setDataSource:self]; // <- This will trigger the tableview to (re)load it's data
}
Next thing is to implement the UITableViewDataSource methods correctly. UITableViewCell *cellOne =[[UITableViewCell alloc] init]; is not returning a valid cell object. You should use at least initWithStyle:. And take a look how to use dequeueReusableCellWithIdentifier:forIndexPath:. A typical implementation would look like this:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = #"Cell";
// Reuse/create cell
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
}
// Update cell contents
cell.textLabel.text = #"Your text here";
cell.detailTextLabel.text=#"text did appear";
return cell;
}
I can't believe I've been doing XCode programming for two years, and still hit this issue.
I had the same problem with XCode 6.1 - I was setting my UITableView's delegate & dataSource in the viewWillAppear function, but none of the delegate functions were kicking in.
However, if I right-clicked on the UITableView on the Storyboard, the circles for delegate and dataSource were empty.
The solution, then, is to hold down the CTRL key, and drag from each of these circles up to the name of your UIView which contains your UITableView:
After doing this, my UITableView happily populated itself.
(So, we're upto v6.1 of XCode now are we ? Do you think Apple ever going to make this thing, you know, friendly...? I would quite like to add a Bookmark in my code... that'd be a nice feature.)

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