首先，我們要在plist文件里添加  View controller-based status bar appearance == NO 默認是YES。

然后你寫更改狀態欄顏色的方法就有效果了

UIStatusBarStyleLightContent為你要設置的顏色

[[UIapplication sharedApplication] setStatusBarStyle:UIStatusBarStyleLightContent animated:YES];

一共有四種情況

    UIStatusBarStyleDefault                                     = 0, // Dark content, for use on light backgrounds

    UIStatusBarStyleLightContent     NS_ENUM_AVAILABLE_IOS(7_0) =1, // Light content, for use on dark backgrounds

    UIStatusBarStyleBlackTranslucent NS_ENUM_DEPRECATED_IOS(2_0,7_0, "Use UIStatusBarStyleLightContent") =1,

    UIStatusBarStyleBlackOpaque      NS_ENUM_DEPRECATED_IOS(2_0,7_0, "Use UIStatusBarStyleLightContent") =2,