IOS 9带来了很多新特性.UIKit也不断在更新,IOS 9苹果引入了 UIStackView,它将让开发
者更容易的创建和管理界面元素.
UIStackView其实就是实现了Auto Layout的一个视图容器,早在Xode5苹果就引入Auto Layout,
为了方便界面在不同尺寸屏幕下的布局,如今UIStackView的引入更加方便了开发者,你只需
要简单设置几个属性就可以完成界面的布局.
假如主视图有三个子视图,IOS 8上需要使用Auto Layout纯代码来布局,要创建五个以上
NSLayoutConstraint来布局.
private void InitConstraint()
{
NSLayoutConstraint constraint = NSLayoutConstraint.Create (view0, NSLayoutAttribute.Leading, NSLayoutRelation.Equal, view1, NSLayoutAttribute.Leading, 20, 0);
this.View.AddConstraint (constraint);
NSLayoutConstraint constraint1 = NSLayoutConstraint.Create (view1, NSLayoutAttribute.Leading, NSLayoutRelation.Equal, view2, NSLayoutAttribute.Leading, 20, 0);
this.View.AddConstraint (constraint1);
NSLayoutConstraint constraint2 = NSLayoutConstraint.Create (view2, NSLayoutAttribute.Leading, NSLayoutRelation.Equal, view3, NSLayoutAttribute.Leading, 20, 0);
this.View.AddConstraint (constraint2);
NSLayoutConstraint constraint3 = NSLayoutConstraint.Create (view3, NSLayoutAttribute.Leading, NSLayoutRelation.Equal, this.View, NSLayoutAttribute.Leading, 20, 0);
this.View.AddConstraint (constraint3);
}IOS 7之前的就需要在中ViewDidLayoutSubviews就得写大量magic number,来控制布局.
public override void ViewDidLayoutSubviews ()
{
base.ViewDidLayoutSubviews ();
nint spacing = 20;
nint width = 50;
nint height = 30;
this.view0.Frame = new CGRect (spacing, spacing, width , height);
this.view1.Frame = new CGRect (view0.Frame.Right + height, spacing, width , height);
this.view2.Frame = new CGRect (view1.Frame.Right + height, spacing, width , height);
this.view3.Frame = new CGRect (view2.Frame.Right + height, spacing, width , height);
}而使用UIStackView只需要简单设置几个属性就可以完成.
private void InitStackView()
{
StackView.Axis = UILayoutConstraintAxis.Horizontal;
StackView.Spacing = 20;
StackView.Alignment = UIStackViewAlignment.Fill;
StackView.Distribution = UIStackViewDistribution.EqualSpacing;
}Axis表示Stack View的子视图是水平排布还是垂直排布.
Alignment控制subview对齐方式.
Distribution定义subview的分布方式.
Spacing 定义子视图之间的最小间距.
想要了解更多关于Xcode7中 UIStackView的内容,推荐阅读 WWDC 2015 的
session 218 Mysteries of Auto Layout, Part 1.在视频前15分钟里,
Jason Yao 介绍了 UIStackView,并且现场制作了一个Demo演示如何操作的.
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