January 2020
Intermediate to advanced
356 pages
6h 4m
Chinese
Content preview from Swift游戏开发经典实例
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视图和菜单
｜
65
View Controller
方法中定义一个
Action
方法，然后在
IB
中将方法连接到现成的
“
exit
”
Segue
即可。
2.4
使用布局约束进行布局
问题
我们有一个包含了其他视图（如按钮）的屏幕，我们想让这些视图在旋屏的时候仍
然待在正确的位置。
解决方案
我们可以通过布局约束来设置视图的位置，步骤如下：
1.
将
view
拖进我们需要的位置。
2.
添加约束。
选中
view
，然后打开
Pin
菜单。
Pin
菜单位于
IB
画布下方，位于底部的一排按
钮中的第二个。就是那个在两条竖线之间夹着一个方块的图标。
3.
设置约束参数为你需要的值。
例如，想将
view
定位到距离屏幕顶部
20
像素和距离屏幕左边
20
像素的位置，
即如图
2-15
所示。
图
2
-
15
：视图将位于左边距
20
，上边距
20
的位置
在上边距栏中输入
20
，左边距栏中输入 20。然后将“
Update Frames
”
栏设置
为
“
Items of New Constraints
”，也就是说当约束一被添加就立即应用该约束，
将
view
移动到约束指定的地方（见图
2-16
）。
66
｜
第
2
章
图
2
-
16
：创建约束
4.
添加约束。
菜单底部的按钮将自动显示为“
Add 3 Constraints
”。点击它，该
view
将自动
固定到右上角位置。
5.
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.