状态栏的字体为黑色：UIStatusBarStyleDefault
状态栏的字体为白色：UIStatusBarStyleLightContent
一、在info.plist中，将View controller-based status bar appearance设为NO
状态栏字体的颜色只由下面的属性设定，默认为白色：
// default is UIStatusBarStyleDefault
[UIApplication sharedApplication].statusBarStyle
解决个别vc中状态栏字体颜色不同的办法
1、在info.plist中，将View controller-based status bar appearance设为NO.
2、在app delegate中：
[UIApplication sharedApplication].statusBarStyle = UIStatusBarStyleLightContent;
3、在个别状态栏字体颜色不一样的vc中
-(void)viewWillAppear:(BOOL)animated{
[UIApplication sharedApplication].statusBarStyle = UIStatusBarStyleDefault;
}
-(void)viewWillDisappear:(BOOL)animated
{
[super viewWillDisappear:animated];
[UIApplication sharedApplication].statusBarStyle = UIStatusBarStyleLightContent;
}
二、在info.plist中，将View controller-based status bar appearance设为YES，或者没有设置。
View controller-based status bar appearance
