iOS橫豎屏問題

 最近突然被告知要適配橫屏，當然最麻煩的是你還不知道iOS工程到底允不允許橫屏，或許說的有點繞口，待會兒看會細說的。其實很想感慨一句：各種奇葩的合理不合理的需求都會遇到的，做爲程序員能做的只有打好基礎才能應對各種情況。
 先說幾個API吧，獲取iOS項目工程自帶的plist文件：

NSDictionary *plist = [[NSBundle mainBundle] infoDictionary];

然後你可以在這裏獲得你的項目配置，有興趣的可以自己看看這個字典裏有哪些key，跟今天我要說的有關的是這個：UISupportedInterfaceOrientations

NSArray *arryplist = plist[@"UISupportedInterfaceOrientations"];

你獲取的這個arryplist裏面的元素是你在項目配置中設置的允許這個app支持哪些方向是直立的、向左橫屏、向右橫屏、顛倒。最多會有這四個元素（因爲工程配置中最多隻支持這個四個方向的）:UIInterfaceOrientationPortrait、UIInterfaceOrientationPortraitUpsideDown、UIInterfaceOrientationLandscapeLeft、UIInterfaceOrientationLandscapeRight。
 通過以上兩行代碼你可以獲取到這個APP支持哪些方向的。


 還要在說個小技巧，你可以通過監聽這個通知實時獲取到屏幕方向改變的消息：UIDeviceOrientationDidChangeNotification

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(changeFrame) name:UIDeviceOrientationDidChangeNotification object:nil];

不要忘了還要移除通知

- (void)dealloc {
    [[NSNotificationCenter defaultCenter] removeObserver:self name:UIDeviceOrientationDidChangeNotification object:nil];
}

這樣當手機屏幕方向改變時候你就可以知道了。
今天最後再說個API通過這個方法你可以獲取到當前手機是橫屏、還是豎屏、其他位置狀態：

[UIDevice currentDevice].orientation

你獲取到的值是個枚舉類型，有這些值：

typedef NS_ENUM(NSInteger, UIDeviceOrientation) {
    UIDeviceOrientationUnknown,
    UIDeviceOrientationPortrait,            // Device oriented vertically, home button on the bottom
    UIDeviceOrientationPortraitUpsideDown,  // Device oriented vertically, home button on the top
    UIDeviceOrientationLandscapeLeft,       // Device oriented horizontally, home button on the right
    UIDeviceOrientationLandscapeRight,      // Device oriented horizontally, home button on the left
    UIDeviceOrientationFaceUp,              // Device oriented flat, face up
    UIDeviceOrientationFaceDown             // Device oriented flat, face down
} __TVOS_PROHIBITED;

配合以上三個技巧，你可以進行橫豎屏的適配：

- (void)changeFrame {
    CGRect rect = [UIScreen mainScreen].bounds;
    CGFloat width = rect.size.width;
    CGFloat height = rect.size.height;
    NSDictionary *plist = [[NSBundle mainBundle] infoDictionary];
    NSArray *arryplist = plist[@"UISupportedInterfaceOrientations"];

    switch ([UIDevice currentDevice].orientation) {
        case UIDeviceOrientationPortrait://這是豎屏
            for (NSString *stringplist in arryplist) {
                if ([stringplist isEqualToString:@"UIInterfaceOrientationPortrait"]) { //判斷這個APP是否允許豎屏，允許了再改變frame

                }
            }

            break;
        case UIDeviceOrientationLandscapeLeft:
            for (NSString *stringplist in arryplist) {
                if ([stringplist isEqualToString:@"UIInterfaceOrientationLandscapeLeft"]) {

                    }

                }
            }

            break;
        case UIDeviceOrientationLandscapeRight:
            for (NSString *stringplist in arryplist) {
                if ([stringplist isEqualToString:@"UIInterfaceOrientationLandscapeRight"]) {

                }
            }
            break;
        default:
            break;
    }
}