• 默认：UIStatusBarStyleDefault

• 白色：UIStatusBarStyleLightContent

• 当前页面状态栏设置为白色

- (void)viewWillAppear:(BOOL)animated{
    [super viewWillAppear:animated];
    [UIApplication sharedApplication].statusBarStyle = UIStatusBarStyleLightContent;//变白
}

-(void)viewWillDisappear:(BOOL)animated{
    [super viewWillDisappear:animated];
    [UIApplication sharedApplication].statusBarStyle = UIStatusBarStyleDefault;//变黑
}