上一節提到了通過通知來處理屏幕視圖的自動翻轉。
藍色的子視圖,在翻轉的情況下觸發界面大小的調整。
還是使用通知機制,即:
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(doRotateAction:)
name:@"UIDeviceOrientationDidChangeNotification"
object:nil];
不過,這裏發現了個問題,當執行通知觸發方法的時候,發現總是執行了多次。其中多出來的情況,設備的方向是不對的:
[UIDevice currentDevice].orientation==UIDeviceOrientationUnknown
如上面代碼,返回的值是UIDeviceOrientationUnknown,也就是0。只許過濾這種情況即可,下面是比較完整的視圖實現代碼:
@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];
}
原文地址:http://marshal.easymorse.com/archives/4723