1、修改App-info.plist(在XCode中General中设置 一样的效果)

	<key>UISupportedInterfaceOrientations</key>
	<array>
		<string>UIInterfaceOrientationPortrait</string>
	</array>

2、AppDelegate中：

- (UIInterfaceOrientationMask)application:(UIApplication *)application supportedInterfaceOrientationsForWindow:(UIWindow *)window {
    return UIInterfaceOrientationMaskAllButUpsideDown;
}

贴一下苹果对这个的解释，可以放心使用：

Discussion

This method returns the total set of interface orientations supported by the app. When determining whether to rotate a particular view controller, the orientations returned by this method are intersected with the orientations supported by the root view controller or topmost presented view controller. The app and view controller must agree before the rotation is allowed.

If you do not implement this method, the app uses the values in the UIInterfaceOrientation key of the app’s Info.plist as the default interface orientations.