I've created a custom UITableViewCell but am having trouble updating the contents of the cell. When I have multiple cells in the table, the table is not drawing the correct images in the cell. The images in each cell should be unique, however I am seeing different cells with the same image. The table seems to be placing the cells at random.
I've checked my data source with NSLog and the names are correct. I can correct the issue when I don't use - (UITableViewCell *)dequeueReusableCellWithIdentifier:(NSString *)identifier, but instead create a new cell each time in - (UITableViewCell *)cellForRowAtIndexPath:(NSIndexPath *)indexPath.
Any suggestion on what I may be doing wrong? Please have a look at my code below.
- (UITableViewCell *)tableView:(UITableView *)_tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
ScoreCell *cell = (ScoreCell *)[_tableView dequeueReusableCellWithIdentifier:#"CellID"];
if (cell == nil)
{
cell = [[[ScoreCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:#"CellID"] autorelease];
}
BoxScore *boxScore = [_gameDayData objectAtIndex:indexPath.row];
[cell setScoreImage:[UIImage imageNamed:boxScore.name]];
return cell;
}
ScoreCell.h
#interface ScoreCell : UITableViewCell
{
UIImage *scoreImage;
}
#property(nonatomic, retain)UIImage *scoreImage;
#end
ScoreCell.m
#implementation ScoreCell
#synthesize scoreImage;
- (void)dealloc
{
[scoreImage release], scoreImage = nil;
}
- (void)drawRect:(CGRect)rect
{
[super drawRect:rect];
[scoreImage drawAtPoint:CGPointMake(5,5)];
}
#end
In addition to the other comments, be sure to implement the -prepareForReuse method in your ScoreCell class. It gets called when the cell is to be reused, at which point you should clear the image. Be sure to call [super prepareForReuse]; in your implementation. This will prevent the cell from being reused with the wrong image.
There are two non-related problems with your image handling.
Scrolling off and on the screen will cause a cell to load the image twice (or a hundred times, depending on the user).
You want a
- (UIImage *)boxScoreImageForIndex:(NSInteger)index
method to (lazy) load, hold on to, and provide the image for the cell.
You also don't want to use imageNamed:, in your case it will cause twice as much memory usage than needed. Use imageWithContentsOfFile: instead.
You are not clearing the previous image. When a cell is dequeued it is not dealloced.
So sometimes the image that was drawn on the cell the times before it show through in front of the new image.
In drawRect you need to clear everything.
Either do:
CGContextClearRect( context , [self bounds] );
Or set clearsContextBeforeDrawing on the cell when it is created.
Related
I'm creating a Settings View for my app, and in that view is a UITableView. I'm creating custom cells to meet my needs, but I'm having issues - only the last cell is getting [layoutSubviews]. Am I doing something wrong?
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
//int type = (indexPath.row == 0?1:0);
//if(indexPath.row == 6) type = 2;
NSLog(#"row %i created", indexPath.row);
TableCell *cell = [[TableCell alloc] initWithType:indexPath.row];
cell.textLabel.text = #"Test cell";
return cell;
}
And in my custom cell:
#implementation TableCell
UIImageView *shadowView;
int row;
- (id) initWithType:(int)type {
row = type;
self = [super initWithStyle:UITableViewCellStyleDefault reuseIdentifier:nil];
self.backgroundColor = [UIColor clearColor];
self.backgroundView = [[UIView alloc] init];
UIImage *shadowImage = [UIImage imageNamed:#"CellShadow"];
shadowImage = [shadowImage resizableImageWithCapInsets:UIEdgeInsetsMake(14, 14, 14, 14)];
shadowView = [[UIImageView alloc] initWithImage:shadowImage];
[self.contentView addSubview:shadowView];
//[self.contentView sendSubviewToBack:shadowView];
NSLog(#"agreed, row %i created", row);
[self layoutSubviews];
return self;
}
- (void) layoutSubviews {
NSLog(#"row: %i", row);
[super layoutSubviews];
shadowView.frame = CGRectMake(
0, 0,
self.contentView.frame.size.width,
self.contentView.frame.size.height
);
}
#end
Continuously, only the last cell #6, is reported when I rotate, or when layoutSubviews should be called. Any suggestions?
Do not call layoutSubviews directly. Use [self setNeedsLayout] or [self layoutIfNeeded]. But do not call these at all in the cell's init method.
Also, do not call [[TableCell alloc] initWithType:indexPath.row]; directly, either. Instead, use...
- (id)dequeueReusableCellWithIdentifier:(NSString *)identifier forIndexPath:(NSIndexPath *)indexPath
Once you've built that cell, you can tell it it's row, but be aware that the cells get recycled as the table scrolls, so you must update that value on every call to cellForRowAtIndexPath.
The cells ought to get layout again (without you making any calls direct or indirect) when the table view is resized.
See the tableview doc here.
You should never call layoutSubviews directly, it will be called automatically by iOS once the cell is ready to display. You should also deque the cell as #danh is recommending. If you're not very comfortable with all this, then I'd really recommend you have a look at the free Sensible TableView framework, which automates creating these kind of settings views (I create mine in a couple of lines, really).
The issue was of my own poor code. Using cell.backgroundView helped a lot here.
Never Call layoutSubviews by yourself. It will be called when ever frames of subview in cell are changed. Even if just change the text of labels in your custom cell wont call layoutSubviews. Ue the deque of cells for reusing for better performance. As it wont allocate cell every time. And in you code looks like has lot of memory issues since cell allocated wont be released and new cell is created.
Basically I'm making a list view that you can add things to the top of. The best way I can think of doing this is to store the UITableViewCells themselves in a NSMutableArray — Because I can simply pull them from the array them with all their data inside the object, and this list view will never be over 10 cells long.
Also note that I'm using Storyboards, hence the initWithCoder use.
The following code is what I'm trying, and it doesn't work:
// This is where my NSMutableArray is initialized:
- (id)initWithCoder:(NSCoder *)aDecoder
{
if (self = [super initWithCoder:aDecoder]) {
if (!_CellsArray) {
UITableViewCell *cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:#"TestCell"];
_CellsArray = [NSMutableArray arrayWithObject:cell];
}
}
return self;
}
//UITableView Delegate & DataSource Methods
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCell *cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:#"TestCell"];
[_CellsArray insertObject:cell atIndex:0];
return [_CellsArray objectAtIndex:indexPath.row];
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
return 10;
}
I realize I may be approaching this in the wrong way, that's why I'm here though :)
Thank you.
edit: fixed a type in the code (TimerCell -> UITableViewCell)
Let's look at the order things get called in and what happens.
Your view controller is unarchived, so your initWithCoder: method is called. This method creates a mutable array and puts one instance of TimerCell into it. Said instance is not further configured (unless you've overridden initWithStyle:reuseIdentifier: to do some configuration).
Your data source method tableView:numberOfRowsInSection: is called, and it tells the table view there are ten rows.
Thus, your tableView:cellForRowAtIndexPath: is called ten times. Each time, it creates a new instance of UITableViewCell and inserts it into your mutable array. (After ten calls, your mutable array contains one TimerCell at index 10 and ten UITableViewCells at indices 0-9.) It does nothing to configure the cell's contents or appearance, then it returns the cell at the specified row index. On the first call, you're asked for row 0, so the cell you just created and inserted at index 0 is returned. On the second call, you're asked for row 1, so the cell at index 1 in your array is returned -- since you just inserted a new cell at index 0, the cell you created on the last call has shifted to index 1, and you return it again. This continues with each call: you return the same unconfigured UITableViewCell ten times.
It looks like you're trying to out-think UIKit. This is almost never a good thing. (It's been said that premature optimization is the root of all evil.)
UITableView already has a mechanism for cell reuse; it's best to just keep track of your own cell content and let that mechanism do its thing. I took so long to type this that other answers have been written describing how to do that. Look to them, or to Apple's documentation or any third-party UITableView tutorial.
Why don't you just store the cell information in an array. Then in the -cellForRowAtIndexPath: method, just extract the data needed to change each cell.
Here is a simple example:
//Lets say you have an init like this that inits some cell information
- (id)initWithCoder:(NSCoder *)aDecoder
{
if (self = [super initWithCoder:aDecoder]) {
cellArray = [NSArray alloc] initWithObjects:#"firstCell",#"secondCell",#"thirdCell",nil];
}
return self;
}
//then for each cell, just extract the information using the indexPath and change the cell that way
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
// Configure the cell...
cell.textLabel.text = [cellArray objectAtIndex:indexPath.row];
return cell;
}
Table views don't store things. Rather, they just ask for the data they want to display, and you typically get that data from elsewhere (like an NSArray, or an NSFetchedResultsController). Just store the things you want into some data container, and let the table display them for you.
// Probably your data model is actually a member of your class, but for purposes of demonstration...
static NSArray* _myArray = [[NSArray alloc] initWithObjects:#"Bob", #"Sally", #"Joe", nil];
- (NSInteger) tableView:(UITableView*)tableView numberOfRowsInSection:(NSInteger)section
{
return [_myArray count];
}
- (UITableViewCell*) tableView:(UITableView*)tableView cellForRowAtIndexPath:(NSIndexPath*)indexPath
{
static NSString* CellIdentifier = #"TestCell";
// Make a cell.
UITableViewCell* cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if( cell == nil ) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
}
// Setup the cell with the right content.
NSString* aString = [_myArray objectAtIndex:[indexPath row]];
cell.textLabel = aString;
return cell;
}
Now if you want more stuff in the list, add it to your array, and you're done.
Edit: On another note, initWithCoder: isn't generally the best place to do initialization for a view controller. Reason being, at the point that it's called, there's a good chance that stuff isn't loaded yet (IBOutlets, for example). I tend to prefer viewDidLoad (don't forget to cleanup in viewDidUnload in that case), or awakeFromNib.
I've got this nasty problem. My class, which is subclassing UITableViewController, has a method which is invoking
(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
The method which is invoking what is above is this one:
- (void) insertInfo:(UIImage *)image
{
self.hotelImage = nil;
self.hotelImage = image;
numRows = numRows + 1;
[self.tableView beginUpdates];
[self.tableView insertSections:[NSIndexSet indexSetWithIndex:0] withRowAnimation:UITableViewRowAnimationFade];
[self.tableView endUpdates];
}
This is how I am creating a cell:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath: (NSIndexPath *)indexPath
{
self.datacell = nil;
self.datacell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleValue1 reuseIdentifier:#"SimpleTableIdentifier"] autorelease];
self.myImageView = nil;
self.myImageView = [[UIImageView alloc] initWithImage:self.hotelImage];
[self.myImageView setFrame:CGRectMake(5, 5, 80, 75)];
[self.datacell.contentView addSubview:self.myImageView];
[self.myImageView release];
self.tableView.userInteractionEnabled = YES;
self.tableView.separatorColor = [UIColor clearColor];
return self.datacell;
}
So, my problem is that when I scroll the table, all images in the table get replaced by a single image at index 0. My guess is that it has something to do with the fact that when cell is created, every image in the section is considered at index 0, but different image is shown when table is created. But when the table is scrolled by user, different images get overtaken by an image the is in the index 0 of the first cell.
This is exactly what happens, the image on the first cell is shown on all cells when the table begins to scroll.
I just don't know how to make every cell retain its unique image when the table is scrolled. My guess is it has something to do with placing image indexPath.section??? But I am not sure. Could somebody please help me with this problem?
Thank you,
Victor.
Effectively you're editing the contents of your table with insertInfo, but not editing its actual source, so as soon as it needs to redraw those cells, they get reverted to its original source. Try using something along the lines of:
self.myImageView=[[UIImageView alloc] initWithImage:[myImageArray objectAtIndex:indexPath.row]];
The fact is that the tableView doesn't keep your cells around. As soon as you scroll them out of view they are gone, released, deallocated as far as you know, and the table view asks the data soucre for new replacement cells. Your cellForRowAtIndexPath is always returning the same cell, independent of what the table view asks for.
You should be storing the images sent to insertInfo into an array, then in cellForRowAtIndexPath, always return the image from the array by index, looked up by indexPath.row and indexPath.section. Every time you scroll, that cellForRowAtIndexPath is called to get all the new cells that weren't on screen, this is why the cells always "change to" the most recent image sent to insertInfo.
Try adding a new file to your project, subclass of UITableViewController, and check out the default code there. You'll find dequeueReusableCellWithIdentifier is also a useful one.
The key concept here is that cellForRowAtIndexPath: is a question, and your code needs to check the values of indexPath.section and indexPath.row, and return a value that belongs to that row/section.
I know this question has been asked before, though I can't seem to find what I want. I have a section in my app where I have a tableview with a textview inside of it. I DO NOT want to have a seperate .xib, .h, and .m files for the tableview cell. The tableview does not need to shrink or grow depending on the amount of text inside the textview. I don't want the textview to be editable either. I hope this isn't too much to ask for, though I'm really stuck at the moment.
To do this, you will need to embed one in your UITableViewCell. But there's no need to create a custom cell. Here is the basic idea of what you will want to do:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
UITextView *comment = [[UITextView alloc] initWithFrame:CGRectMake(cell.frame.origin.x, cell.frame.origin.y, cell.frame.size.width, tableView.rowHeight)];
comment.editable = NO;
comment.delegate = self;
[cell.contentView addSubview:comment];
[comment release];
}
return cell;
}
You will, of course, need to set your rowHeight if you don't want the standard 44pt height that comes with the cell. And if you want actual cells, you'll need to add your own logic so that only the cell you want is a textView, but this is the basic idea. The rest is yours to customize to your fitting. Hope this helps
EDIT: to bypass the textView to get to your cell, there are two ways to go about this.
1) you can make a custom textView class and overwrite touchesBegan to send the message to super:
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
[super touchesBegan:touches withEvent:event];
}
this will send the touch events to its superview, which would be your tableView. Considering you didn't want to make custom UITableViewCells, I imagine you probably don't want to make a custom textView class either. Which leads me to option two.
2) when creating the textView, remove comment.editable = NO;. We need to keep it editable, but will fix that in a delegate method.
In your code, you will want to insert a textView delegate method and we'll do all our work from there:
EDIT: changing this code to use with a UITableViewController
- (BOOL)textViewShouldBeginEditing:(UITextView *)textView {
// this method is called every time you touch in the textView, provided it's editable;
NSIndexPath *indexPath = [self.tableView indexPathForCell:textView.superview.superview];
// i know that looks a bit obscure, but calling superview the first time finds the contentView of your cell;
// calling it the second time returns the cell it's held in, which we can retrieve an index path from;
// this is the edited part;
[self.tableView selectRowAtIndexPath:indexPath animated:NO scrollPosition:UITableViewScrollPositionNone];
// this programmatically selects the cell you've called behind the textView;
[self tableView:self.tableView didSelectRowAtIndexPath:indexPath];
// this selects the cell under the textView;
return NO; // specifies you don't want to edit the textView;
}
If that's not what you wanted, just let me know and we'll get you sorted out
I'm loading a UITableViewCell that contains two tagged labels. The user will leave the current view, containing the following code and go to another view. A name value is set there and the user comes back to this view (code below). I assign the name they set in the other view to the name label. That works but I get a new label misaligned on top of my other labels. It seems I'm keep two versions of this cell. Not quite sure. Any suggestions on what might be causing that sort of behavior?
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
UITableViewCell *cell = nil;
if(indexPath.section == 0)
{
cell = [tableView dequeueReusableCellWithIdentifier:#"CellNameIdentifier"];
if (cell == nil) {
[[NSBundle mainBundle] loadNibNamed:#"CellentName" owner:self options:nil];
cell = cellName;
//self.cellName = nil;
}
}
return cell;
}
- (void)viewDidAppear:(BOOL)animated {
UILabel *startdate = (UILabel *)[cellName viewWithTag:1];
startdate.text = aName;
[super viewDidAppear:animated];
}
From the look of this code it is less likely that you are getting "a new label misaligned on top of my other labels" and more like the drawing is failing to repaint on top of things properly. To make this work, you can try calling [tableView reloadData] or using an observer, but I think there is a better way.
You should be able to pass the object into your other view, modify the object (instead of the label) and move the data around that way. In other words on the table view, it loads the objects, and inside of cellForRowAtIndexPath it loads the cells and sets the label names using the object data. Push in the second view and pass the object as a property. Manipulate this property all you want on that screen and when you pop the view, there is no special logic. The first table view again displays whatever is saved inside that object you were manipulating.