When a view will disappear I would like to collect the values of some of the switches in my table view, I have pointers to the index path, cell, and control how do I get a pointer to the table view so I can properly point the cell pointer... if I'm thinking correctly I should be able to then get the value of the control pretty quickly throught these pointers... unless somebody has a better idea. If I'm thinking incorrectly I would still like to know how to point to a specific tableView.
Thanks,
Thanks for the answer, it is a regular view, so I made a property of UITableView, and then I used the interface builder to connect thisTableView property to the actual tableView.
If there's a better way let me know. Thanks,
Wjy don't you have a pointer to your UITableView? Assuming you are using a UITableViewController the class provides one for you (self.tableView). If not you probably should just add a property in your UIViewContoller sublcass for the tableview and put it there.
The table view is, after all, one of the large objects that view controller is controlling and it lives across multiple method calls. Representing your relationship to it with a retained property asserts ownership, just make sure to release it in dealloc and in viewDudUnload if it came from a nib.
Having said that, currently you can generally find a UITableView from a UITableViewCell by asking the UITableViewCell for it superView. This is a bad idea since there is no guarantee there won't be some intermediary cells in the future, since hierarchy of cells you did not layout yourself is an internal implementation detail (a lot of apps broke on 3.0 because they walked around inside Apple's view hierarchies and something changed).
Related
I'm trying to make a custom table view. I have a UIScrollView loaded up with UIViews. I would like to recreate the reusable cell functionality that a tableview has. And I'm wondering what might be a good way to do this.
I was thinking that when the UIViews are scrolled off screen I'll remove them from the Subview, and when I need another I'll just add it. However I'm not sure what method might be the best to do this in.
I could check to see the views location in scrollViewDidScroll: but I'm not sure if this would be the best thing to check over and over again. If anyone has any suggestions or helpful tips that would be really awesome.
Thanks!
One reason why scrollViewDidScroll is less than ideal choice is that your scroll view subclass will then need to be its own delegate. That will deny the users of that class the chance to be the delegate (easily, at least).
The better place to check this is in overriding layoutSubviews. And yes, like scrollViewDidScroll, it gets called a lot! But if you think about it, the only way to detect with certainty if any subview has been scrolled off, is to check when any scrolling occurs.
So the key is to be as efficient as you can checking. The first thing I'd try is fast enumeration of the subviews, asking if each frame transformed by contentOffset falls within the parent's bounds (using CGRectIntersectsRect). If not, add it to your reuse pool and remove it from superview.
Subclass UIScrollView and override setContentOffset. That's where the scrollViewDidScroll message comes from in the original UITableView, and that's where you can implement your own logic.
Edit: you might want to study the source code for PSTCollectionView, which is not a custom UITableView but a custom UICollectionView.
I´m new trying to make some apps using objective c, so I´ve an idea using uitableview but I don't imagine how can I get this.
I´m trying to do something like you do in a spreadsheet where you have a fixed header and the first column too
So when scroll the uitableview vertically the header will stay visible at top of the table and rows will change
And finally when you scroll in horizontal direction the first cell of the row will stay visible and will change the header depending of how you scroll the uitableview
I hope you could give me an idea how to get this, because I don't imagine how to do this, also I don´t have a lot of experience with this programming language.
Thanks!
In a non-grouped table, section headers "stick" at the top of the table as the table scrolls. You can provide a custom UIView (or sub-class thereof) for a section header through the delegate method –tableView:viewForHeaderInSection:. This header view could be created on-the-fly programmatically or loaded from a NIB file. Either way, you can have it contain whatever you want, even update it as the app runs (provided you have given yourself access through ivars or class variables to the views contained in your header view.) If you go this route, you'll want to be clever about allocating resources that comprise this view, so that you are not constantly allocating new resources! This delegate method can be called frequently, and on all but the first call you could simply return the previously created (but updated as and if necessary) header view.
UITableView isn't designed to do this, although I am sure you could figure out some way eventually.
My approach would be to use a fixed UIView of some sort (possibly a UILabel, etc) in a UIViewController's nib as the header/locked cell, and add the UITableView under that. You couldn't then use a UITableViewController, but would have to implement the delegate and dataSource methods in your UIViewController, and use a UISwipeGestureRecognizer to pick up the gestures from the tableView and update the other views.
I've done this by adding a UIView that mimics the first cell in my table. In my case I am using a subclass of UITableViewCell, but that is perhaps not relevant. Normally this view is hidden with an alpha of 0.
If you view controller is the delegate of the UITableView then it will also be the delegate for the inherited UIScrollView. So in your view controller you can implement scrollViewDidScroll. When the scrollView's contentOffset is positive I set my custom view's alpha to 1 (I also do some small size tweaks to make sure there is a perfect match), and when the contentOffset returns to 0 or negative, I reset the alpha back to 0.
prepend the first row of data in your array to what ever in the first row is your headings, put the text in bold with attributed text, It wont be sticky but you will have headings...
I was working with the grouped table view , and i wanted different controls for every row i.e switch control for 1st,radio button for 2nd ,checkbox for 3rd and so on.. how can this be implemented programmatically that is without using interface builder
thanks in advance
CharlieMezak said is right, you need to create in UIControls directly in cellForRowAtIndexPath , and add as subviews to contentView of the cell
For reference see the link below
http://www.e-string.com/content/custom-uitableviewcells-interface-builder
the link specifies the code to create cells programmatically as well as using IB.
Table View Programming Guide for iOS
Read the programing guide, and remember to use different CellIdentifier for each type of cell.
This is a pretty vague question.
Obviously you need to provide the cells to the tableview in its cellForRowAtIndexPath delegate/datasource method. So, either in that method or during the initialization of your view controller, build the UITableViewCell instances that you need, adding the various controls that you want to them as subviews and connecting the controls to your view controller so you can detect when they have been changed. Then just return the appropriate cell in the cellForRowAtIndexPath method.
Personally, I think it's a lot easier to use IB in cases like this. Just create an IBOutlet instance variable for each custom cell you want, and return the right cell in cellForRowAtIndexPath.
How do you know that you scrolled using the UITableViewIndex ?
I have some basic info to show on my cells, and when I jump/scroll I need to retrieve info about thoses cells by a request for a group(page) of items.
So in order to request only thoses I've stopped to, I need a way to know that I've stopped scrolling (I used scrollViewDidEndDecelerating) but with the UITableViewIndex we ca just jump to another index or scroll though them.
The only feedback that you get is in the UITAbleViewDelegate protocol - none of these report that the table view has scrolled.
However, you will get calls to tableView:cellForRowAtIndexPath: calls to your data source - this will tell you that the table view has moved enough to want a new cell.
Also, you have the visibleCells property of the UITableView itself to see where you are in the table?
It might help if you put more detail into your question - why do you need to know that a scroll has happened?
The UITableView inherits from UIScrollView so you can also implement the UIScrollViewDelegate methods such as scrollViewDidScroll. When the table view scrolls, these will be called.
However, if you explain why you need to know whether the table view has scrolled, there might be a better answer.
Edit:
From your updated question, it's still not totally clear whether you need the scrollview delegate methods.
If you just need to update the contents of the cells themselves, put that in cellForRowAtIndexPath and the table view will automatically call it when the cell comes into view.
If you need to update something outside the table view, you might still be able to do it in cellForRowAtIndexPath or you can handle scrollViewDidEndDecelerating: and then use the table view's visibleCells or indexPathsForVisibleRows methods to get the list of cells currently visible.
I'm looking for an in-depth breakdown/explanation of the iphone's view usage. Like, what controllers have what types of views, how they relate (child <> parent), how they can be nested, added and removed, etc.
Preferably something with some pictures would be nice too (I'm a visual learner).
But yeah, in-depth, technical, explanations of the iphone view system when used in IB/Obj-c would be awesome.
Also, feel free to give your breakdown or post to resources and I'll do the research.
Thanks
EDIT:
Ok, I'll be more specific. Is the View a stack - is it a queue? What does it look like when I call addtosubview?
What happens if the view isn't a full UIView, but say a smaller UI Control - will it be visible?
Say I have a UIView with a UITabView (2 items) and one content view is a UITtableView.
What's the parent view? What is the order of the children? Is that all dependent on how I add them to the view? In this case, the UITabBar control takes care of handling the views when I select the button.
When I call insertSubview how do I know what index to position it at?
This will be a good place to start (go from here to UIViewController and others that seem relevant). A UIView can contain many subviews of any type (they all inherit from UIView). To nest views, you add the subview to the superview [superview addSubview:subview]. You should also read up on Model-View-Controller.
Edit:
This SO question might also shed some light on the matter.
Edit edit:
Best I can do to answer your questions:
UIViews have an iVar subviews which is an array of subviews. Each of these also has such an array and can contain UIViews.
I assume you mean not full screen, generally, the topmost view is a UIWindow, and to this you add any UIView subclass you like, such as UISlider.
Your UIView has a subview UITabView, I don't know specifically, but I would guess it has two subviews, one of which is visible at a time, and one of these is the UITableView. Order is dependent on the order you add them in, and they will overlap each other depending on this order, but it can be changed with sendSubviewToBack and bringSubviewToFront.
If you want a specific view order, you're probably better off using insertSubview:aboveSubview: and the equivalent below, rather than at index.
Hope some of this helps.
Ok, I'll be more specific. Is the View a stack - is it a queue? What does it look like when I call addtosubview?
I like to think of it as a tree. The window is the root node, and it has any number of subviews. Those subviews can have any number of their own subviews, going down as far as necessary to create the full interface. The addSubview and removeFromSubview methods manipulate a view's "children".
What happens if the view isn't a full UIView, but say a smaller UI Control - will it be visible?
My understanding is that everything on the screen is a subclass of UIView, even the UIControl objects. Therefore, they behave mostly the same.
Say I have a UIView with a UITabView (2 items) and one content view is a UITtableView. What's the parent view? What is the order of the children? Is that all dependent on how I add them to the view? In this case, the UITabBar control takes care of handling the views when I select the button.
I'm not sure: David's answer has more info that should help.
When I call insertSubview how do I know what index to position it at?
I wouldn't worry about it: most of the time you just want addSubview and you won't care about the internal order.