最近在做项目时需求是只有在某一个页面可以横竖屏来回切换 其他页面竖屏显示

遇到的问题是在手机横屏的状态下 打开app 页面是错乱的,

下面是我的解决方案
1、在Xcode中进行设置

w1.png

2、在AppDelegate.h中添加旋转属性

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

在AppDelegate.m中添加转屏的代理方法

- (UIInterfaceOrientationMask)application:(UIApplication *)application supportedInterfaceOrientationsForWindow:(nullable UIWindow *)window
{
    //  如果设置了allowRotation属性，支持全屏
    if (_allowRotation == YES) {
        return UIInterfaceOrientationMaskAll;
    }else{
        return UIInterfaceOrientationMaskPortrait;//默认全局不支持横屏
    }
}

3、基类navigation代码:

- (BOOL)shouldAutorotate {
    return self.topViewController.shouldAutorotate;
}
 
- (UIInterfaceOrientationMask)supportedInterfaceOrientations {
    return self.topViewController.supportedInterfaceOrientations;
}
 
- (UIInterfaceOrientation)preferredInterfaceOrientationForPresentation {
    return self.topViewController.preferredInterfaceOrientationForPresentation;
}

4、项目里写了一个公共的UIViewController，名字为BaseViewController,创建的BaseViewController继承UIViewController 在该viewController里进行了如下设置:

-(BOOL)shouldAutorotate{
    
    return YES;
}
- (UIInterfaceOrientationMask)supportedInterfaceOrientations
{
    return UIInterfaceOrientationMaskPortrait;
}
- (UIInterfaceOrientation)preferredInterfaceOrientationForPresentation
{
    return UIInterfaceOrientationPortrait;
}

-(BOOL)shouldAutorotate这个方法是重点 如果设置为NO,在横屏手机的状态下打开app页面还是错乱的
5、如果你的应用的根控制器是TabVC，就把下面这段代码放到TabVC根控制器下，

- (BOOL)shouldAutorotate{
    return self.selectedViewController.shouldAutorotate;
}
- (UIInterfaceOrientationMask)supportedInterfaceOrientations {
    return self.selectedViewController.supportedInterfaceOrientations;
}

- (UIInterfaceOrientation)preferredInterfaceOrientationForPresentation {
    return self.selectedViewController.preferredInterfaceOrientationForPresentation;
}

这里就实现了横屏状态下打开app竖屏展示的效果。
如果想在某一个页面里进行横竖屏切换，可以进行如下设置

-(void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];
    [SimplifyAnswerAppDelegate sharedInstance].allowRotation = YES;
}

- (void)viewWillDisappear:(BOOL)animated {
    [super viewWillDisappear:animated];
    [SimplifyAnswerAppDelegate sharedInstance].allowRotation = NO;
}

[SimplifyAnswerAppDelegate sharedInstance]是我在appdelegate里面写的一个类方法，SimplifyAnswerAppDelegate是我把appDelegate进行了重新命名，具体方法实现如下：

+ (SimplifyAnswerAppDelegate *)sharedInstance {
    return (SimplifyAnswerAppDelegate *)[UIApplication sharedApplication].delegate;
}

如果是用的APPDelegate,可以这么写

AppDelegate * appDelegate = (AppDelegate *)[UIApplication sharedApplication].delegate;
 appDelegate.allowRotation = NO;  // 关闭横屏仅允许竖屏

到这里就实现了前面说的所有页面默认竖屏，部分页面横屏显示的需求。