转https://www.jianshu.com/p/ea1682e80003

先讲需求：

APP中所有界面支持竖屏，只有在一个界面，点击一个btn之后变成横屏，再点就是竖屏。
在网上找了一些方法，发现实现不了，遂问了一个做过这个功能的朋友，得到朋友的支持之后，顺利解决这一问题

在这里因为是要全局界面都是支持竖屏，其他的不支持，在Xcode里面的配置

 

Xcode配置

然后就是在AppDelegate中添加属性和方法，

#import

@interface AppDelegate : UIResponder

@property (strong, nonatomic) UIWindow *window;
//是否强制横屏
@property (nonatomic, assign) BOOL isForceLandscape;
//是否强制竖屏
@property (nonatomic, assign) BOOL isForcePortrait;

@end

添加属性

在AppDelegate中添加方法 

-(UIInterfaceOrientationMask)application:(UIApplication *)application supportedInterfaceOrientationsForWindow:(UIWindow *)window{
if (self.isForceLandscape) {
return UIInterfaceOrientationMaskLandscape;
}else if (self.isForcePortrait){
return UIInterfaceOrientationMaskPortrait;
}else{
return UIInterfaceOrientationMaskPortrait;
}
}

一下是viewController中，即需要转换屏幕方向的.m文件的代码：

#import "ViewController.h"
#import "AppDelegate.h"
@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.

//     _currentOrient = [UIApplication  sharedApplication].statusBarOrientation;

    UIButton * button = [UIButton buttonWithType:UIButtonTypeCustom];
    [button setTitle:@"转一转" forState:UIControlStateNormal];
    [button setTitleColor:[UIColor redColor] forState:UIControlStateNormal];
    [button addTarget:self action:@selector(changeFrame:) forControlEvents:UIControlEventTouchUpInside];
    button.translatesAutoresizingMaskIntoConstraints = NO;
    [self.view addSubview:button];

   NSLayoutConstraint * centerX = [NSLayoutConstraint constraintWithItem:button attribute:NSLayoutAttributeCenterX relatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeCenterX multiplier:1.0 constant:0];
   NSLayoutConstraint * centerY = [NSLayoutConstraint constraintWithItem:button attribute:NSLayoutAttributeCenterY relatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeCenterY multiplier:1.0 constant:0];
   NSLayoutConstraint * width = [NSLayoutConstraint constraintWithItem:button attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationEqual toItem:nil attribute:NSLayoutAttributeNotAnAttribute multiplier:1.0 constant:100];
   NSLayoutConstraint * height =[NSLayoutConstraint constraintWithItem:button attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:nil attribute:NSLayoutAttributeNotAnAttribute multiplier:1.0 constant:44];

    [NSLayoutConstraint activateConstraints:@[centerX,centerY,width,height]];
    centerY.active = YES;
    centerX.active = YES;
    width.active = YES;
    height.active = YES;

}
// 允许自动旋转
-(BOOL)shouldAutorotate{
    return YES;
}
// 横屏时是否将状态栏隐藏
-(BOOL)prefersStatusBarHidden{
    return NO;
}
-(void)changeFrame:(UIButton *)btn{

    btn.selected = !btn.selected;

    if (btn.selected) {
        [self forceOrientationLandscapeWith:self];
    }else{
        [self forceOrientationPortraitWith:self];
    }
}
// 横屏 home键在右边
-(void)forceOrientationLandscapeWith:(UIViewController *)VC{

    AppDelegate *appdelegate=(AppDelegate *)[UIApplication sharedApplication].delegate;
    appdelegate.isForcePortrait=NO;
    appdelegate.isForceLandscape=YES;
    [appdelegate application:[UIApplication sharedApplication] supportedInterfaceOrientationsForWindow:VC.view.window];

    //强制翻转屏幕，Home键在右边。
    [[UIDevice currentDevice] setValue:@(UIInterfaceOrientationLandscapeRight) forKey:@"orientation"];
    //刷新
    [UIViewController attemptRotationToDeviceOrientation];
}
// 竖屏
- (void)forceOrientationPortraitWith:(UIViewController *)VC{

    AppDelegate *appdelegate=(AppDelegate *)[UIApplication sharedApplication].delegate;
    appdelegate.isForcePortrait=YES;
    appdelegate.isForceLandscape=NO;
    [appdelegate application:[UIApplication sharedApplication] supportedInterfaceOrientationsForWindow:VC.view.window];

    //强制翻转屏幕
    [[UIDevice currentDevice] setValue:@(UIDeviceOrientationPortrait) forKey:@"orientation"];
    //刷新
    [UIViewController attemptRotationToDeviceOrientation];
}

这样就实现了点击切换屏幕方向的需求，嘻嘻！！