?

iPhone或iPad可以支持4種朝向
??? UIInterfaceOrientationPortrait
??? UIInterfaceOrientationPortraitUpsideDown
??? UIInterfaceOrientationLandscapeLeft
??? UIInterfaceOrientationLandscapeRight

究竟支持哪幾個朝向，由view controller的shouldAutorotateToInterfaceOrientation函數來指定，每當設備的朝向發生變化時，這個方法都會被調用。

對于iPhone程序，應該防止用戶在通話時拿倒電話，不支持UIInterfaceOrientationPortraitUpsideDown
因此函數實現為：
- (BOOL)shouldAutorotateToInterfaceOrientation:? (UIInterfaceOrientation) interfaceOrientation {
????? return (interfaceOrientation != UIInterfaceOrientationPortraitUpsideDown);
}
對于iPad，應該支持所有的朝向，因此函數實現為
- (BOOL)shouldAutorotateToInterfaceOrientation:? (UIInterfaceOrientation) interfaceOrientation {
????? return true；
}

實現對Rotation的支持有三種方法：
1. 設置UI元素的Autosize Attribute，類似于.NET form的dock
2. 重新構造UI元素大小和位置
3. 不同的朝向使用不同的view

使用Autosize Attribute

Inner box中的紅色箭頭和UI元素的size有關，如果橫向的紅色的箭頭成為實線，則窗口尺寸變化時UI元素的寬度也會變化，如果橫向紅色箭頭為虛線，則窗口寬度變化時UI元素的寬度保持不變。垂直方向同理。
Inner box周圍的短線變成實線時，表明UI元素和它所在的view的邊緣的距離保持不變。

下圖中的UI對象的高度將會隨著view的高度而變化，同時UI元素相對于View的上下邊距不變

對應的UI設置為

重新構造UI元素的大小和位置

- (void) willAnimateRotationToInterfaceOrientation :? (UIInterfaceOrientation)
interfaceOrientation duration:(NSTimeInterval)duration {
?? if (interfaceOrientation == UIInterfaceOrientationPortrait
??????? || interfaceOrientation == UIInterfaceOrientationPortraitUpsideDown)
? {
????? button1.frame = CGRectMake(20, 20, 125, 125);
????? button2.frame = CGRectMake(175, 20, 125, 125);
????? button3.frame = CGRectMake(20, 168, 125, 125);
????? button4.frame = CGRectMake(175, 168, 125, 125);
????? button5.frame = CGRectMake(20, 315, 125, 125);
????? button6.frame = CGRectMake(175, 315, 125, 125);
?? }
?? else
?? {
????? button1.frame = CGRectMake(20, 20, 125, 125);
????? button2.frame = CGRectMake(20, 155, 125, 125);
????? button3.frame = CGRectMake(177, 20, 125, 125);
????? button4.frame = CGRectMake(177, 155, 125, 125);
????? button5.frame = CGRectMake(328, 20, 125, 125);
????? button6.frame = CGRectMake(328, 155, 125, 125);
?? }
}

切換View

為了支持兩個View，需要在View controll中生成兩套outlet
@interface SwapViewController : UIViewController {
????? UIView *landscape;
????? UIView *portrait;
????? // Foo
????? UIButton *landscapeFooButton;
????? UIButton *portraitFooButton;
????? // Bar
????? UIButton *landscapeBarButton;
????? UIButton *portraitBarButton;
}
在Interface builder中刪除Xcode自動生成的view，從library中拖兩個view 到main window上。分別命名為Portrait和Landscape.
選中File’s Owner，Control-drag 到Portrait和Landscape，連接outlet

動態加載view
#define degreesToRadians(x) (M_PI * (x) / 180.0)

- (void) willAnimateRotationToInterfaceOrientation : (UIInterfaceOrientation)
interfaceOrientation duration:(NSTimeInterval)duration {
if (interfaceOrientation == UIInterfaceOrientationPortrait) {
self.view = self.portrait;
self.view.transform = CGAffineTransformIdentity;
self.view.transform = CGAffineTransformMakeRotation(degreesToRadians(0));#define degreesToRadians(x) (M_PI * (x) / 180.0)
self.view.bounds = CGRectMake(0.0, 0.0, 320.0, 460.0);
}
else if (interfaceOrientation == UIInterfaceOrientationLandscapeLeft) {
self.view = self.landscape;
self.view.transform = CGAffineTransformIdentity;
self.view.transform = CGAffineTransformMakeRotation(degreesToRadians(-90));
self.view.bounds = CGRectMake(0.0, 0.0, 480.0, 300.0);
}
else if (interfaceOrientation == UIInterfaceOrientationPortraitUpsideDown) {
self.view = self.portrait;
self.view.transform = CGAffineTransformIdentity;
self.view.transform = CGAffineTransformMakeRotation(degreesToRadians(180));
self.view.bounds = CGRectMake(0.0, 0.0, 320.0, 460.0);
}
else if (interfaceOrientation == UIInterfaceOrientationLandscapeRight) {
self.view = self.landscape;
self.view.transform = CGAffineTransformIdentity;
self.view.transform = CGAffineTransformMakeRotation(degreesToRadians(90));
self.view.bounds = CGRectMake(0.0, 0.0, 480.0, 300.0);
}
}

iPhone開發之Rotation