IOS横竖屏控制与事件处理

公司App里面有个需求，即所有界面都是竖屏，且不允许横屏切换，唯独有一个图表界面允许横屏。那么，根据此需求处理如下：

首先，确保App本身应该允许转屏切换：

再次，我的App里面都是走UINavigationController进行界面push切换的，所以首先创建一个UINavigationController的子类，并设定允许转屏：

 @implementation AppExtendNavigationController
 - (void)viewDidLoad {
 [super viewDidLoad];
 // Do any additional setup after loading the view.
 }
 - (void)didReceiveMemoryWarning {
 [super didReceiveMemoryWarning];
 // Dispose of any resources that can be recreated.
 }
 #pragma mark 转屏方法重写
 -(UIInterfaceOrientationMask)supportedInterfaceOrientations
 {
 return [self.viewControllers.lastObject supportedInterfaceOrientations];
 }
 -(UIInterfaceOrientation)preferredInterfaceOrientationForPresentation
 {
 return [self.viewControllers.lastObject preferredInterfaceOrientationForPresentation];
 }
 -(BOOL)shouldAutorotate{
 return self.visibleViewController.shouldAutorotate;
 }

最后，在你不想转屏切换的ViewController上重写以下方法：

 #pragma mark 转屏方法 不允许转屏
 -(UIInterfaceOrientationMask)supportedInterfaceOrientations
 {
 return UIInterfaceOrientationMaskPortrait ;
 }
 - (BOOL)shouldAutorotate
 {
 return NO;
 }
 -(UIInterfaceOrientation)preferredInterfaceOrientationForPresentation
 {
 return UIInterfaceOrientationPortrait;
 }
 - (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation{
 return NO;
 }

在你想转屏切换的ViewController上可以照这样重写（允许左右横屏以及竖屏）：

 - (BOOL)shouldAutorotate {
 return YES;
 }
 -(UIInterfaceOrientationMask)supportedInterfaceOrientations
 {
 return UIInterfaceOrientationMaskAll;
 }
 - (UIInterfaceOrientation)preferredInterfaceOrientationForPresentation
 {
 return UIInterfaceOrientationPortrait;
 }
 - (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
 {
 return YES;
 }

另外，在ViewController中对于转屏事件可以参见下面的方法进行捕获：

 - (void)viewWillTransitionToSize:(CGSize)size withTransitionCoordinator:(id<UIViewControllerTransitionCoordinator>)coordinator
 {
 [super viewWillTransitionToSize:size withTransitionCoordinator:coordinator];
 [coordinator animateAlongsideTransition:^(id<UIViewControllerTransitionCoordinatorContext> context) {
 //计算旋转之后的宽度并赋值
 CGSize screen = [UIScreen mainScreen].bounds.size;
 //界面处理逻辑
 self.lineChartView.frame = CGRectMake(, , screen.width, 200.0);
 //动画播放完成之后
 if(screen.width > screen.height){
 NSLog(@"横屏");
 }else{
 NSLog(@"竖屏");
 }
 } completion:^(id<UIViewControllerTransitionCoordinatorContext> context) {
 NSLog(@"动画播放完之后处理");
 }];
 }

区分当前屏幕是否为横竖屏的状态，其实通过判断当前屏幕的宽高来决定是不是横屏或者竖屏：

竖屏时：宽<高

横屏时：宽>高

以上在IOS8、9中测试通过