网上的一些方法在我这行不通，
比如：
UIApplication.sharedApplication().statusBarStyle = UIStatusBarStyle.LightContent
1、Set the UIViewControllerBasedStatusBarAppearance to YES in the .plist file.
2、In the viewDidLoad do a [self setNeedsStatusBarAppearanceUpdate];
3、Add the following method:
-(UIStatusBarStyle)preferredStatusBarStyle{
return UIStatusBarStyleLightContent;
}
最后终于有个方法OK
1、设置Info.plist中的View controller-based status bar appearance为YES
2、然后在AppDelegate.swift中的
func application(application: UIApplication!, didFinishLaunchingWithOptions launchOptions: NSDictionary!) -> Bool
方法中加入：
UINavigationBar.appearance().barStyle = UIBarStyle.Black
OK，就是这么简单。这样状态栏的字体就变成白色了！