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又一个iOS屏幕切换的示例

在iOS屏幕变换的处理，已经提到了通过通知来处理屏幕视图的自动翻转。

这里再写一个。

蓝色的子视图，在翻转的情况下触发界面大小的调整。

还是使用通知机制，即：

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

不过，这里发现了个问题，当执行通知触发方法的时候，发现总是执行了多次。其中多出来的情况，设备的方向是不对的：

[UIDevice currentDevice].orientation==UIDeviceOrientationUnknown

如上面代码，返回的值是UIDeviceOrientationUnknown，也就是0。只许过滤这种情况即可，下面是比较完整的视图实现代码：

@implementation ContentView

-(id)initWithCoder:(NSCoder *)aDecoder{
    self = [super initWithCoder:aDecoder];
    if (self) {
        [[NSNotificationCenter defaultCenter] addObserver:self
                                                 selector:@selector(doRotateAction:)
                                                     name:@”UIDeviceOrientationDidChangeNotification”
                                                   object:nil];
    }
    return self;
}

-(void) doRotateAction:(NSNotification *) notification{
    if([UIDevice currentDevice].orientation!=UIDeviceOrientationUnknown){
        NSLog(@”do rotate action: %d”,[[notification object] orientation]);
        if([UIDevice currentDevice].orientation==UIDeviceOrientationPortrait||
           [UIDevice currentDevice].orientation==UIDeviceOrientationPortraitUpsideDown){
            self.frame=CGRectMake(self.frame.origin.x, self.frame.origin.y, 200, 200);
        }else{
            self.frame=CGRectMake(self.frame.origin.x, self.frame.origin.y, 600, 500);
        }
    }
}

-(void)dealloc{
    [[NSNotificationCenter defaultCenter] removeObserver:self];
}

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