iPhone Landscape FAQ and Solutions

Question

There has been a lot of confusion and a set of corresponding set of questions here on SO how iPhone applications with proper handling for Landscape/Portrait mode autorotatio

Answer 1

I'm developing an iPad app that displays vertically scrolling gallery view of an array of items upon startup. In landscape mode there are 4 items across. In portrait there are three. When turning the iPad orientation it is supposed to refresh the gallery to have the items fit neatly across the screen. Then I double tap on an item to drill down to a modal view of that item. Then I do stuff with that item. Finally I dismiss the modal view.

During the refresh or orientation change the gallery view calculates the number of items to display based on the screen width (or height) and the current orientation from UIViewController.interfaceOrientation.

I was having a problem getting this to work correctly. Sometimes it would display only two items in landscape orientation after I dismissed the modal dialog.

At first I was using the UIViewController.view.frame.size values to calculate the number of gallery items. When the modal view was dismissed this frame size was incorrect e.g. the width and height had been reversed even though the orientation had not changed while the modal dialog was displayed.

I switched to using the application delegate ([[UIApplication sharedApplication] delegate]] and taking the window.frame.size to calculate the number of gallery items to display across. The window.frame.size stays correct under orientation changes and modal dialogs. The gallery items display correctly now.