第一步:

首先在工程文件里设置如下:

image.png

第二步:

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;//是否允许转向
• AppDelegate.m中添加方法

- (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;  // 这里是屏幕要旋转的方向
    }else{
        return (UIInterfaceOrientationMaskPortrait);
    }
}

第三步:

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;//(以上2行代码,可以理解为打开横屏开关)
    [self setNewOrientation:YES];//调用转屏代码

• 具体实现方法:

- (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"];
    }
}

• 在页面离开的时候恢复竖屏

- (void)viewWillDisappear:(BOOL)animated{
    [super viewWillDisappear:animated];
    AppDelegate * appDelegate = (AppDelegate *)[UIApplication sharedApplication].delegate;
    appDelegate.allowRotation = NO;//关闭横屏仅允许竖屏
    [self setNewOrientation:NO];
}