UITableView Did Load (Done drawing the cells) - iphone

Question
How can you detect when the Table View is done drawing the cells?
Issue
I got two labels within the contentView of an UITableViewCell. The size of these labels are dynamic. I was able to do so by subclassing UITableViewCell, in the drawRect method I adjust the frames of the two labels depending on their content. Now I want to align all the second labels.
My Thoughts in Steps
Determine the content in the table view and let it load automatically.
Run through the table view cells and determine the x position of the second label within the UITableViewCell that is the furtherest away.
Store this x position and when any cell is drawn use this x position to place the second label.
The problem is that if I use the following code:
for (int row = 0; row < [self.tableView numberOfRowsInSection:section]; row++) {
UITableViewCustomCell *cell = (UITableViewCustomCell *)[self.tableView cellForRowAtIndexPath:[NSIndexPath indexPathForRow:row inSection:0]];
NSLog ([cell.labelTwo description]);
}
The second label has not yet been drawn, meaning I can't determine the size of the frame and thus can not find the proper x position to align all second labels.
I have tried subclassing the UITableViewController and looking at events such as viewDidLoad and viewDidAppear unfortunatly also in these events the cells aren't drawn yet.
What I Want ...
What I want is for the table view to draw the cells at least once so I can determine the sizes of the labels within the table view cell. I thought to accomplish this by looping through all the cells with cellForRow, but although it successfully returns the cell the content is not drawn yet meaning the frame remains with a width of zero.
Does anyone have a solution?
Thanks in advance,
Mark

Try calling sizeWithFont: on the contents of these labels to get the max width before you draw anything. You should be able to use it later in your cellForRowAtIndexPath: to adjust the width as you need.
I would recommend you reconsider using UITableViewCellStyleValue2 cells instead and attempt to configure the textLabel and detailTextLabel. I had a similar situation and this is how I did it.

First off, you really ought to just pick an explicit, fixed position at which the first label ends and the second one begins, based on what you know about the minimum and maximum lengths of the text that will be put in those labels. That would eliminate this problem entirely.
But if you want a solution: use the sizeWithFont: method or one of its cousins (see the Xcode docs). Specifically, loop through the values that will go in the first labels, apply sizeWithFont to each, and keep track of the largest width you see. (I'm assuming you have access to the values before they go in the cells; since they're dynamic, they must be passing through the table view controller, no?)
Now you have the value you seek, without having to perform the extremely wasteful operation of creating a bunch of cell objects and never using them for their intended purpose.

I think what you need to do is to add a viewController to the have the UITableViewController control the UITableViewCell itself so that you can capture the events of the labels loading. The viewController will have references to both labels so it can adjust them accordingly in response to -viewDidAppear.
I've never done this but a UITableViewCell is a view like any other so you should be able to set up a controller for it. You might need to manually activate the controller since you have no navigation controller to do it for you in this context.

Related

Show a label over the limits of a UITableViewCell

I'd like to use a UItableView to show a day Calendar. Each row corresponds to one hour. I need to show the hour between 2 cell of my tableview.
Like this :
(source: free.fr)
And this is my UITableViewCell :
(source: free.fr)
In the first screenshot, it works perfectly but if I scroll down then scroll up, my time label is cut like this :
(source: free.fr)
Have you any tips to figure out this problem using a tableView ?
The way you lay out your cell now is fragile, because the order of painting the cells on screen matters a lot. Try moving the content up so that your buttons are flush with the top of the cell, and the time label fits into the cell entirely. Add a thin header view to your table to make the top cell appear normal. Keeping the content of a cell entirely within its bounds should help you maintain reasonable scrolling speeds.
EDIT : You could also put a second clipped label at the top of your cell, and make its content identical to that of the label in the prior row. You would need to take special care to hide that label in the top row, but otherwise this should make your table immune to changes in the rendering order of its cells.
Make the background color of your cell clear. As you scroll up the z ordering of your cells get reversed and the lower cells overlap the higher ones causing this clipping.

iPhone Dev - How to make a UITableView the exact height to fit all of the cells in it

I have the following:
I would like to make it so that the tableview stops right at the "So" cell, instead of having all the blank cells under it (the big plan is to have a bunch of multiple choice questions like the one in that pic, all on top of one another on one scrollview). I'm guessing I need to set the tableView's frame, but I was wondering if there was an easy way to calculate at runtime the exact height of the portion of the tableview where the cells are implemented (the ones with text in the pic). It's tricky because I made it so that each cell's height can change to accommodate the amount of text in it. Anyone have any advice?
There are two appproaches you can take.
Best and easiest.
1. Add a footer view to the table so it will not draw the rows after the last row. a blank footer view will do.
//Add empty view to hide trailing row seperators
UIView *emptyView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 320, 0)];
emptyView.backgroundColor = [UIColor whiteColor];
[tableView setTableFooterView:emptyView];
[emptyView release];
2.Check how many rows you have in the tableview and calculate the tableheight and change the frame of table view.
There isn't a tableView:sizeOfAllCells: function if that is what you are looking for. From your question it sounds like you to adjust the size of your table so you can put other content on bottom of it.
You are correct is saying that you want to alter your UITableView's frame property to match the height.
[table setFrame:CGRectMake(0,0,table.frame.size.width,heightOfCells)];
There are a few things you could do though. If you had an array of all the cells, you could loop through it real quick and add the height of each of them. You could (I don't particularly recommend it though) loop though the number of sections and rows you have, using tableView:cellForRowAtIndex: instead of having an array of cells, and get the heights that way. If each cell is the same height (sounds like its possible it wont be) you could just do some simple math to figure out the height. Lastly, you could keep a dictionary or array of heights and update it in the tableView:cellForRowAtIndex: so if the content changes, it updates the size, but then you would have to call a reloadData. Those are just a few ideas of ways to solve this particular problem.
Here's a hack (so wait to see if a better solution comes along):
Use numberOfSections to get the number of sections (if you later change to grouped style), and then add up the heights of rectForSection: for each of the sections (in plain style, just take rectForSection:0). Maybe add a bit to this for the separators.

iPhone - Custom TableViewCell height calculated off cell text

I'm creating a custom cell in the cellForRowAtIndex function and filling it with my dynamic text. The height of the cell is variable based upon this text so I need to user the heightForRowAt function, but in that function I don't have the cell. I can create a new one and fill it with the text and then call my calculateHeight function on it but then I'm creating 2 cells for each row.
Anyone have a better method? Cache the cells yourself in the cellForRow function in a dictionary by row index and use that? Is cellForRow called before heightForRow?
I've managed to crash Xcode4 twice so far playing around with this so am hoping someone has done this already.
tableView:heightForRowAtIndexPath:
is called before
tableView:cellForRowAtIndexPath:
Creating two cells is a possible solution, but creating two cells isn't a very effective method. However, you don't need the cell to calculate the height; All you need is the string.
You'll probably want to use
sizeWithFont:constrainedToSize:
on your string to calculate the height.
I could provide details on how to do that, but you should be able to figure it out from reading the documentation.
What you do is you make a class method on your custom cell (for instance), which knows the values of how things (statically sized things) will be set, and does some math to determine given the offsets of the text view for instance, it can tell you how big the cell needs to be after calculating how high your string will be given a font.

How to configure iOs UITextViews and UILabels so that their height is determined by their content

I am basically trying to find the correct way to design a UITableViewCell that has two UITextViews and three UILabels inside it. The two UITextViews have dynamic content and their size cannot be determined until runtime.
I have tried various methods of recalculating the height of my UITextViews based on the content that is loaded in them at runtime, and though very laborious and inane, I have gotten that to work, but they then bleed over the UILabels positioned in the xib below them.
Do I really have to recalculate the y coordinates of every UILabel after calculating the new size of the UITextViews? Is there a way to simply have the elements in the xib 'push' the elements below them down based on their new size?
What is the correct approach to configuring a UITableViewCell with multiple dynamic text views so that my entire application is not comprised of code to calculate heights and coordinates?
Or is the answer that I should not be putting more than one dynamic UITextView in the same UITableViewCell ?
I have used something like this for a cell to calculate its height in
tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
function
CGSize labelSize = [self.comments sizeWithFont:[UIFont fontWithName:#"Verdana" size:17.0]
constrainedToSize:CGSizeMake(280.0f, MAXFLOAT)
lineBreakMode:UILineBreakModeWordWrap];
return labelSize.height + 20;
+20 is for padding.
and also if you are having every cell like the one you mention above, than you can create a class of UITableViewCell with following UIView elements inside it.
iOS doesn't seem to have any sort of flow layout engine -- at least none that I can think of.
If, however, your labels are located at the bottom of your UITableViewCell, you might be able to get away with setting the UILabel's autoresizingMask mask property to UIViewAutoresizingFlexibleBottomMargin so that the UILabels will anchor itself at the bottom. This is assuming that you already adjusted the size of the UITableViewCell to fit the entire controls. Otherwise, I think the best way to handle this is to recalculate the y coordinates of the labels.
I found it useful to add this sort of behavior as a category on UIView so a view can resize one of its subviews to fit some arbitrary text, and optionally resize the parent view to fit the newly enlarged subview as needed.
http://blog.carbonfive.com/2009/07/10/resizing-uilabel-to-fit-text/

Programmatically determining padding for grouped UITableView

Is there a way to programmatically get a UITableView's 'grouped' style padding?
I'd like to size some things in my screen but I need to know how far left or right to place them on a grouped UITableView's UITableViewCell.
Since you are using the grouped style for your table view, you should be able to use the rectForSection: method to get the CGRect where that section will be drawn. You may have to already have added your cells to your view, however.
CGRect sectionRect = [tableView rectForSection:0];
int paddingLeft = sectionRect.origin.x;
As I see it, 'grouped' style padding == the origin of cell.contentView. but the value is assigned by table view only in tableView:willDisplayCell:forRowAtIndexPath: and is equal to 10 on iPhone/iPod Touch. querying it in cellForRowAtIndexPath: results in 0.