如何修复“Freeform Size模拟指标在Xcode 4.2之前不可用”警告？

Question

Since a couple of weeks, I've been using XCode 4.2 with projects created with previous XCode 3.x versions.

When creating some custom iPad views, I often use the "freeform" attribute of Interface Builder to be able to have views with an arbitrary size.

But then, I get build the following build warnings: "warning: Attribute Unavailable: Freeform Size simulated metrics are not available prior to Xcode 4.2."

My question is: how can I fix these warnings?

ps: First, I assumed it meant my project wouldn't be backward-compatible with earlier versions of XCode (which doesn't bother me at all) and tried to tell Xcode so, by setting the Project Format to XCode 4.2-compatible only. Unfortunately, the dropdown menu for the project format only suggests "XCode 3.2-compatible" and "XCode 3.1-compatible".

Answer 1

Open the .xib file in question and show the Utilities pane. Click on the File Inspector tab and under Interface Builder Document you'll see a Development field. Change it to Xcode 4.2.