iOS中关于UIWindow和statusbar的设置问题

- (UIStatusBarStyle)preferredStatusBarStyle​- (void)setNeedsStatusBarAppearanceUpdate​

// TestView.h#import@interface TestView : UIView@property (nonatomic, strong) NSString *clickTitle;​- (void)show;@end// TestView.m​#import "TestView.h"@implementation TestView{  UIWindow *window;  UIButton *clickBtn;}- (void)makeWindow{  window = [[UIWindow alloc] init];  window.windowLevel = UIWindowLevelStatusBar + 1;  window.backgroundColor = [UIColor clearColor];  [window makeKeyAndVisible];  TestVC *rootVC = [[TestVCalloc] init];  rootVC.view.backgroundColor = [UIColorcolorWithRed:0green:0blue:0alpha:0.5];  UINavigationController *navi = [[UINavigationControlleralloc]initWithRootViewController:rootVC];  window.rootViewController = navi;  navi.navigationBarHidden = YES;  self.frame = CGRectMake(0, 0, window.frame.size.width - 40, 80);  self.center = window.center;  [rootVC.view addSubview:self];}- (instancetype)initWithFrame:(CGRect)frame{  if (self = [super initWithFrame:frame]) {    clickBtn = [UIButton buttonWithType:UIButtonTypeCustom];  }  returnself;}- (NSString *)clickTitle{  if (!_clickTitle) {    _clickTitle = @"clicks";  }  return_clickTitle;}- (void)show{  [clickBtn setTitle:self.clickTitleforState:UIControlStateNormal];  [selfmakeWindow];}// TestVC.m#import "TestVC.h"@interfaceTestVC ()@end@implementation TestVC- (void)viewDidLoad {  [super viewDidLoad];  // Do any additional setup after loading the view.  [self setNeedsStatusBarAppearanceUpdate];}- (UIStatusBarStyle)preferredStatusBarStyle{  return UIStatusBarStyleLightContent;}