Tab bar application and UIScrollView

Question

Hi Everyone,
I am creating a tabbar application.
I have 5 tabs already setup, and now one of the tabs needs a few more fields appended to the bottom of the view.
I am using a single NIB file with all the views built inside of it.
What I need to do is take the second tab and add a UIScrollView to it, so I can add the additional fields to the bottom.
I would like to stick with using IB....
Here is the stack I have setup, please advise where I would insert the UIScrollView
App
First Responder
App Delegation
Window
Tab Bar Controller
Tab Bar
Main View Controller (Log)
Selected Main View Controller (Permit)
Scroll View
View
Tab Bar Item (Permit)
Main View Controller (Tags)
Main View Controller (Release)
Main View Controller (Other)
I have placed the ScrollView both within the View, and, as shown, a view as a child of the scroll view...
I have set the height of the view and the scroll view at 800px
Please advise on what I am missing in this.
Thanks
tony

Answer 1

alt-088 wrote:
I have all the views loaded within the same XIB file.
It's usually better to make a separate xib for each view. The most important reason for this is memory management. Firstly, all the views defined in MainWindow.xib are loaded at startup. This means a view will be loaded even if its tab is never selected. Views defined in a separate xib won't be loaded unless and until they're needed.
It's also much easier to unload a view if its defined in a separate xib, since the view, along with all its subviews, can be reloaded at any time by simply reloading the xib (e.g. by initing a new controller with [initWithNibName:bundle:|http://developer.apple.com/iphone/library/documentatio n/UIKit/Reference/UIViewControllerClass/Reference/Reference.html#//appleref/occ/instm/UIViewController/initWithNibName:bundle:]). This is especially important when the controller receives a low memory warning. For example, the default implementation of [didReceiveMemoryWarning|http://developer.apple.com/iphone/library/documentatio n/UIKit/Reference/UIViewControllerClass/Reference/Reference.html#//appleref/occ/instm/UIViewController/didReceiveMemoryWarning] will unload a view defined in a separate xib because the method knows how to reload that view.
Another reason for separate xibs is that the main xib needs to be loaded before the app can launch. Anytime you remove an object from MainWindow.xib, you'll reduce launch time.
should i have a view for each of the tabs in the main form?
You probably already have a view for each of the tabs, so I assume you meant to ask, "Should i have a separate xib file for each controller which is connected to the tab bar controller in MainWindow.xib?"
If I restated the question correctly, the answer is yes, as explained above.
Note the Tab Bar App template demonstrates both ways to define each controller's view. The first view controller's view is defined in MainWindow.xib. The second controller's view is defined in SecondView.xib. The difference between these setups can be seen in the Attributes Inspector. If you select the First View Controller (most easily done in the xib (icon) window if the View Mode switch is in the Center position to display the view hierarchy) and open the Attributes Inspector, you'll see the NIB Name selection is blank. If you then select the Second View Controller, the NIB Name selection will be "SecondView".
You could move the First View Controller's view to a separate xib by making a new xib named "FirstView.xib" (File->New File..->iPhone OS->User Interface->View XIB), deleting the View object under the First View Controller in MainWindow.xib, and then setting the NIB Name selection in the Attributes Inspector to "FirstView". After that, open FirstView.xib, select File's Owner and set its Class to FirstViewController in the Identity Inspector, then connect the View object to the 'view' outlet of File's Owner.
You can make a separate xib for any of your views in the same way. Of course in the case of a scrolling view, you would add a UIScrollView object and connect it to the 'view' outlet of File's Owner, then connect the UIView object to the 'contentView' outlet of File's Owner as discussed previously (after setting the Class of File's Owner to a custom class that has a contentView IBOutlet).
Whenever you make a separate xib for one of your views, _make sure File's Owner is set to the same class as its parent controller object in MainWindow.xib_.
\- Ray