iOS開發 - 戲說旋屏

橫豎屏切換，視圖亂了怎么辦？

首先，我們必須了解一下下列4種狀態，它們被用來描述設備旋轉方向：

對于旋屏的處理，大致分為如下幾種情況和思路：

也許，你不需要旋屏支持，而希望鎖定屏幕

-(BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    return NO;
}

也許，你需要支持旋屏，或者支持部分方向的旋屏

-(BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation { 
       return (interfaceOrientation != UIInterfaceOrientationPortraitUpsideDown);
}

也許，你的view有張背景圖，旋屏時系統幫助你拉伸了圖片，但是卻沒有管你的其它部件，比如button,你希望直接改變button的大小和位置

-(void)willAnimateRotationToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation duration:(NSTimeInterval)duration
{
    if (UIInterfaceOrientationIsPortrait(toInterfaceOrientation)) {
        NSLog(@"現在是豎屏");
        [btn setFrame:CGRectMake(213, 442, 340, 46)];
    }
    if (UIInterfaceOrientationIsLandscape(toInterfaceOrientation)) {
        NSLog(@"現在是橫屏");
        [btn setFrame:CGRectMake(280, 322, 460, 35)];
    }
}

也許，你并不希望用絕對坐標去約束控件，而是希望讓它通過旋轉自己適應屏幕的旋轉

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    UIDevice *device = [UIDevice currentDevice]; 
    [device beginGeneratingDeviceOrientationNotifications];
    //利用 NSNotificationCenter 獲得旋轉信號 UIDeviceOrientationDidChangeNotification
    NSNotificationCenter *ncenter = [NSNotificationCenter defaultCenter]; 
    [ncenter addObserver:self selector:@selector(orientationChanged) name:UIDeviceOrientationDidChangeNotification object:device];
}

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    return (interfaceOrientation != UIInterfaceOrientationPortraitUpsideDown);
}

-(void)rotation_btn:(float)n
{
    UIButton *robtn = self.btn;
    robtn.transform = CGAffineTransformMakeRotation(n*M_PI/180.0);
}

-(void)orientationChanged
{
    UIDeviceOrientation orientaiton = [[UIDevice currentDevice] orientation];

    switch (orientaiton) {
        caseUIDeviceOrientationPortrait:             
            [self  rotation_btn:0.0];
            break;
        caseUIDeviceOrientationPortraitUpsideDown:  
            [self  rotation_btn:90.0*2];
            break;
        caseUIDeviceOrientationLandscapeLeft:     
            [self  rotation_btn:90.0*3];
            break;
        caseUIDeviceOrientationLandscapeRight:  
            [self  rotation_btn:90.0];
            break;
        default:
            break;
    }
}

也許，你需要autoresizesSubviews = YES

也許，你希望橫豎屏有不同的布局效果，需要準備2份Subview，在不同狀態去替換

當然不要忘記，需要調節設定圖示中的1、2處，