Autorotation and Autosizing

配置应用级别的旋转方向——Global Setting

方法：点击项目-General-Deployment-Device Orientation

It doesn’t necessarily mean that every view in your application will use all of the selected orientations; but if you’re going to support an orientation in any of your application’s views, that orientation must be selected here.

配置视图级别的旋转方向——Local Setting

方法：ViewController.m中

- (NSUInteger)supportedInterfaceOrientations
{
    return (UIInterfaceOrientationMaskPortrait | UIInterfaceOrientationMaskLandscapeLeft);
}

同一个App的不同视图，旋转方向的限制可能不一样。只能在应用级别的旋转方向上限制更多，比如应用级别不支持Upside-down，视图级别也一定不行。

附，旋转方向：

• UIInterfaceOrientationMaskPortrait
• UIInterfaceOrientationMaskLandscapeLeft
• UIInterfaceOrientationMaskLandscapeRight
• UIInterfaceOrientationMaskPortraitUpsideDown
• UIInterfaceOrientationMaskLandscape
• UIInterfaceOrientationMaskAll
• UIInterfaceOrientationMaskAllButUpsideDown

旋转，横竖视图排版一样

添加四个角（1，2，5，6）的Label

全选四个角（1，2，5，6）的Label，选择Editor -> Resolve Auto Layout Issues -> Add Missing Constraints

添加中间（3，4）的Label，对齐

左中（3）Editor -> Align -> Vertical Center in Container

右中（4）Editor -> Resolve Auto Layout Issues -> Add Missing Constraints

（1，2）加背景颜色，调整它们的宽度（随便，不一定等宽）

（1，2） Editor -> Pin -> Horizontal Spacing(无论怎么旋转都不等宽)

（1，2） Editor -> Pin -> Widths Equally（无论怎么旋转都等宽）

旋转，横竖视图排版不一样

创建SingleViewApplication，在View的File Inspector中取消AutoLayout，我们要利用代码实现布局。
在Main.storyboard中拖入一个View和4个Button，并设置该View的背景颜色。

ViewController.m中实现代码

旋转的时候就自动调用

- (void)willAnimateRotationToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation duration:(NSTimeInterval)duration
{
    [self adjustLayout:toInterfaceOrientation];
}

- (void)adjustLayout:(UIInterfaceOrientation)toInterfaceOrientation
{
    if (UIInterfaceOrientationIsPortrait(toInterfaceOrientation))
    {
        [self layoutPortrait];
    }
    else
    {
        [self layoutLandscape];
    }
}

static const CGFloat btnHeight = ;
static const CGFloat btnWidth = ;
static const CGFloat spacing = ;

- (void)layoutPortrait
{
    CGRect b = self.view.bounds;
    CGFloat contentHeight = CGRectGetHeight(b)-btnHeight*-spacing*;
    CGFloat contentWidth = CGRectGetWidth(b) - spacing*;
    self.contentView.frame = CGRectMake(spacing, spacing, contentWidth, contentHeight);

    CGFloat btn1x = spacing;
    CGFloat btn2x = CGRectGetWidth(b)-spacing-btnWidth;
    CGFloat btn1y = contentHeight+*spacing;
    CGFloat btn2y = btn1y+btnHeight+spacing;

    self.btn1.frame = CGRectMake(btn1x, btn1y, btnWidth, btnHeight);
    self.btn2.frame = CGRectMake(btn2x, btn1y, btnWidth, btnHeight);
    self.btn3.frame = CGRectMake(btn1x, btn2y, btnWidth, btnHeight);
    self.btn4.frame = CGRectMake(btn2x, btn2y, btnWidth, btnHeight);
}

- (void)layoutLandscape
{
    CGRect b = self.view.bounds;
    CGFloat contentHeight = CGRectGetHeight(b)-spacing*;
    CGFloat contentWidth = CGRectGetWidth(b) - spacing*-btnWidth;
    self.contentView.frame = CGRectMake(spacing, spacing, contentWidth, contentHeight);

    CGFloat btnx = CGRectGetWidth(b)-spacing-btnWidth;
    CGFloat btny1 = spacing;
    CGFloat btny4 = CGRectGetHeight(b)-spacing-btnHeight;
    CGFloat btny2 = btny1+(btny4-btny1)/3.0;
    CGFloat btny3 = btny2+(btny4-btny1)/3.0;

    self.btn1.frame = CGRectMake(btnx, btny1, btnWidth, btnHeight);
    self.btn2.frame = CGRectMake(btnx, btny2, btnWidth, btnHeight);
    self.btn3.frame = CGRectMake(btnx, btny3, btnWidth, btnHeight);
    self.btn4.frame = CGRectMake(btnx, btny4, btnWidth, btnHeight);
}

viewDidLoad只在程序启动时调用了一次；屏幕旋转的时候没有调用它，调用的是- (void)willAnimateRotationToInterfaceOrientation:duration:

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
　　//处理启动时不是默认竖屏的情况。
    UIApplication *app = [UIApplication sharedApplication];
    UIInterfaceOrientation currentOrientation = app.statusBarOrientation;
    [self adjustLayout:currentOrientation];
}

效果