Develop Tools: xCode 5.1

I write a demo for app settings feature. The tutorial url is here. 

When I add a icon into app icon and build the code, I got this error "The app icon set named "AppIcon" did not have any applicable content.".

In this URL, I got the root cause.

Reason: iOS app must mach the iOS icon size policy in here.

Solution: 

1.Delete App Icon segment in Images.xcassets.

2.Create a new App Icon segment in Images.xcassets. (It will add all iOS device icon size needness)

3.Modify the icon size to mach the icon size.

4.Drop into the icon set.

5.Rebuild.