IOS6之AutoLayout（三）

继续介绍Image的相对布局实现：

直接上代码：

 @interface ViewController1 ()
 {
     float aspect;
 }
 @property (nonatomic, strong) UIImageView *imageView;
 @end

 - (void)viewDidLoad
 {
     [superviewDidLoad];
     self.view.backgroundColor = [UIColorwhiteColor];

     UIImage *image = [UIImageimageNamed:@"beautiful_girl.png"];

     self.imageView = [[UIImageViewalloc]initWithImage:image];
     self.imageView.translatesAutoresizingMaskIntoConstraints =NO;
     [self.viewaddSubview:self.imageView];

     aspect =self.imageView.frame.size.height/self.imageView.frame.size.width;

     [selfautoLayoutImage];
 }

 - (void) autoLayoutImage
 {
 //图片的中心点X坐标与self.view的中心点X左边相等
     NSLayoutConstraint *constraint = [NSLayoutConstraint
                                       constraintWithItem:self.imageView
                                       attribute:NSLayoutAttributeCenterX
                                       relatedBy:NSLayoutRelationEqual
                                       toItem:self.view
                                       attribute:NSLayoutAttributeCenterX
                                       multiplier:1.0f
                                       constant:0.0f];

     [self.view addConstraint:constraint];

 //图片的中心点Y坐标与self.view的中心点Y左边相等
     constraint = [NSLayoutConstraint
                   constraintWithItem:self.imageView
                   attribute:NSLayoutAttributeCenterY
                   relatedBy:NSLayoutRelationEqual
                   toItem:self.view
                   attribute:NSLayoutAttributeCenterY
                   multiplier:1.0f
                   constant:0.0f];

 [self.viewaddConstraint:constraint];

 //图片的高度和self.view的高度相等
     constraint = [NSLayoutConstraint
                   constraintWithItem:self.imageView
                   attribute:NSLayoutAttributeHeight
                   relatedBy:NSLayoutRelationEqual
                   toItem:self.view
                   attribute:NSLayoutAttributeHeight
                   multiplier:1.0f
                   constant:0.0f];

 [self.viewaddConstraint:constraint];


 //     为了保持当屏幕旋转时候，图片的纵横比不变，如果不设置比例，图片比例会改变（multiplier:aspect）
     constraint = [NSLayoutConstraint
                   constraintWithItem:self.imageView
                   attribute:NSLayoutAttributeHeight
                   relatedBy:NSLayoutRelationEqual
                   toItem:self.imageView
                   attribute:NSLayoutAttributeWidth
                   multiplier:aspect
                   constant:0.0f];

 [self.imageViewaddConstraint:constraint];
 }

如果有地方不理解，可以参考IOS6之AutoLayout（一）、IOS6之AutoLayout（二）。

转载请保留，原文链接：http://write.blog.csdn.net/postedit/8861958

若发现有不合适或错误之处，还请批评指正，不胜感激。