-(void)viewWillAppear:(BOOL)animated
 {
[super viewWillAppear:animated];
self.navigationController.navigationBar.hidden = NO;

if ([[UIDevice currentDevice] respondsToSelector:@selector(setOrientation:)]) {
    SEL selector = NSSelectorFromString(@"setOrientation:");
    NSInvocation *invocation = [NSInvocation invocationWithMethodSignature:[UIDevice instanceMethodSignatureForSelector:selector]];
    [invocation setSelector:selector];
    [invocation setTarget:[UIDevice currentDevice]];
    int val = UIInterfaceOrientationLandscapeRight;
    [invocation setArgument:&val atIndex:2];
    [invocation invoke];
}

 }
-(void)viewWillDisappear:(BOOL)animated
{
[super viewWillDisappear:animated];
self.navigationController.navigationBar.hidden = NO;

if ([[UIDevice currentDevice] respondsToSelector:@selector(setOrientation:)]) {
    SEL selector = NSSelectorFromString(@"setOrientation:");
    NSInvocation *invocation = [NSInvocation invocationWithMethodSignature:[UIDevice instanceMethodSignatureForSelector:selector]];
    [invocation setSelector:selector];
    [invocation setTarget:[UIDevice currentDevice]];
    int val = UIInterfaceOrientationPortrait;
    [invocation setArgument:&val atIndex:2];
    [invocation invoke];
}

 }
- (BOOL)shouldAutorotate
{
return YES;
}
-(UIInterfaceOrientation)preferredInterfaceOrientationForPresentation
{
return UIInterfaceOrientationLandscapeLeft;
}

- (NSUInteger)supportedInterfaceOrientations
{
return UIInterfaceOrientationMaskLandscape;
}

2.跳转系统设置
1，如何跳到指定的设置界面，例如设置WiFi的时候，想直接跳到WiFi设置界面。

  在URL Types添加 一个叫prefs的URL Schemes

2.添加这段代码(把下面的Bundle identifier替换为相应的字段即可)

 [[UIApplication sharedApplication] openURL:[NSURL URLWithString:@"prefs:root=Bundle identifier"]];

可以直接打开对应App的设置页面
3.对应的字段

蜂窝网络：prefs:root=MOBILE_DATA_SETTINGS_ID
VPN — prefs:root=General&path=Network/VPN
Wi-Fi：prefs:root=WIFI
定位服务：prefs:root=LOCATION_SERVICES
个人热点：prefs:root=INTERNET_TETHERING
关于本机：prefs:root=General&path=About
辅助功能：prefs:root=General&path=ACCESSIBILITY
飞行模式：prefs:root=AIRPLANE_MODE
锁定：prefs:root=General&path=AUTOLOCK
亮度：prefs:root=Brightness
蓝牙：prefs:root=General&path=Bluetooth
时间设置：prefs:root=General&path=DATE_AND_TIME
FaceTime：prefs:root=FACETIME
设置：prefs:root=General
键盘设置：prefs:root=General&path=Keyboard
iCloud：prefs:root=CASTLEiCloud
备份：prefs:root=CASTLE&path=STORAGE_AND_BACKUP  
语言：prefs:root=General&path=INTERNATIONAL
定位：prefs:root=LOCATION_SERVICES
音乐：prefs:root=MUSICMusic 
Equalizer — prefs:root=MUSIC&path=EQMusic 
Volume Limit — prefs:root=MUSIC&path=VolumeLimit
Network — prefs:root=General&path=Network
Nike + iPod — prefs:root=NIKE_PLUS_IPOD
Notes — prefs:root=NOTES
Notification — prefs:root=NOTIFICATIONS_ID
Phone — prefs:root=Phone
Photos — prefs:root=Photos
Profile —prefs:root=General&path=ManagedConfigurationList
Reset — prefs:root=General&path=Reset
Safari — prefs:root=Safari
Siri — prefs:root=General&path=Assistant
Sounds — prefs:root=Sounds
Software Update —    prefs:root=General&path=SOFTWARE_UPDATE_LINK
Store — prefs:root=STORET
witter — prefs:root=TWITTER
Usage — prefs:root=General&path=USAGE
Wallpaper — prefs:root=Wallpaper