第一步

在AppDelegate中添加方法关闭横竖屏切换,方法如下

AppDelegate.h中外露一个属性

@property( nonatomic , assign ) BOOL allowRotation;//标识是否允许转向

AppDelegate.m中增加如下方法

- (UIInterfaceOrientationMask)application:(UIApplication *)application supportedInterfaceOrientationsForWindow:(nullable UIWindow *)window{
    if (_allowRotation == YES) {   // 如果属性值为YES,仅允许屏幕向左旋转,否则仅允许竖屏
        return UIInterfaceOrientationMaskLandscapeRight;  // 此处是屏幕要旋转的方向
    }else{
        return (UIInterfaceOrientationMaskPortrait);
    }
}

第二步

在需要强制横屏的页面写上如下代码:

• 在viewDidLoad 方法设置如下:

AppDelegate * appDelegate = (AppDelegate *)[UIApplication sharedApplication].delegate;
appDelegate.allowRotation = YES;//(打开AppDelegate里的横屏开关)
[self setNewOrientation:YES];//调用转屏代码

• 实现setNewOrientation方法:

- (void)setNewOrientation:(BOOL)fullscreen{
    if (fullscreen) {
        NSNumber *resetOrientationTarget = [NSNumber numberWithInt:UIInterfaceOrientationUnknown];
        [[UIDevice currentDevice] setValue:resetOrientationTarget forKey:@"orientation"];
        NSNumber *orientationTarget = [NSNumber numberWithInt:UIInterfaceOrientationLandscapeRight];
        [[UIDevice currentDevice] setValue:orientationTarget forKey:@"orientation"];
    }else{
        NSNumber *resetOrientationTarget = [NSNumber numberWithInt:UIInterfaceOrientationUnknown];
        [[UIDevice currentDevice] setValue:resetOrientationTarget forKey:@"orientation"];
        NSNumber *orientationTarget = [NSNumber numberWithInt:UIInterfaceOrientationPortrait];
        [[UIDevice currentDevice] setValue:orientationTarget forKey:@"orientation"];
    }
}

注意点

有些导航控制器push出来的页面，如果在导航控制器里写了侧滑代理及手势，可能会导致部分强制横屏页面没法横屏，此时需要把导航控制器里侧滑手势代码屏蔽删除即可。

- (void)viewDidLoad {
    [super viewDidLoad];
    
    //就这句话导致了push出来的页面无法强制横屏
    //self.interactivePopGestureRecognizer.delegate = self;
    
    self.navigationBar.barTintColor = [UIColor whiteColor];//64B4FA//64C83C//7F9CFF
    [self.navigationBar setTitleTextAttributes:@{NSFontAttributeName:T18Font_M, NSForegroundColorAttributeName:C16}];
}