blocks|key|534200|text|Objective-C|type|unstyled|depth|inlineStyleRanges|entityRanges|data|534201|yourSubView.center+=+CGPointMake(yourView.frame.size.width++/+2,+
+++++++++++++++++++++++++++++++++yourView.frame.size.height+/+2);|code-block|syntax|javascript|534202|斯威夫特|534203|yourSubView.center+=+CGPoint(x:+yourView.frame.size.width++/+2,
+++++++++++++++++++++++++++++y:+yourView.frame.size.height+/+2)|534204|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

<h3>Objective-C</h3>

<pre><code>yourSubView.center = CGPointMake(yourView.frame.size.width / 2, 
 yourView.frame.size.height / 2);
</code></pre>

<h3>Swift</h3>

<pre><code>yourSubView.center = CGPoint(x: yourView.frame.size.width / 2,
 y: yourView.frame.size.height / 2)
</code></pre>

blocks|key|317234|text|你可以做到这一点，并且它总是有效的：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|317235|child.center+=+[parent+convertPoint:parent.center+fromView:parent.superview];|code-block|syntax|javascript|317236|对于Swift：|317237|child.center+=+parent.convert(parent.center,+from:parent.superview)|317238|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

You can do this and it will always work:

<pre><code>child.center = [parent convertPoint:parent.center fromView:parent.superview];
</code></pre>

And for Swift:

<pre><code>child.center = parent.convert(parent.center, from:parent.superview)
</code></pre>

blocks|key|534302|text|在视图和子视图中使用相同的中心是最简单的方法。你可以这样做，|type|unstyled|depth|inlineStyleRanges|entityRanges|data|534303|UIView+*innerView+=+....;
innerView.view.center+=+self.view.center;
[self.view+addSubView:innerView];|code-block|syntax|javascript|534304|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Using the same center in the view and subview is the simplest way of doing it. You can do something like this,

<pre><code>UIView *innerView = ....;
innerView.view.center = self.view.center;
[self.view addSubView:innerView];
</code></pre>

blocks|key|534368|text|​|type|unstyled|depth|inlineStyleRanges|entityRanges|data|534369|📷|atomic|offset|length|534370|534371|将此自动调整蒙版大小设置为您的内部视图。|534372|entityMap|0|IMAGE|mutability|IMMUTABLE|imageUrl|https://ask.qcloudimg.com/http-save/yehe-900000/fc07ac597840c078ff69f09945a36ea0.png|imageAlt^0|0|0|1|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@$E|U|F|V|1|W]]|A|$]]|$1|G|3|4|5|6|7|X|8|@]|9|@]|A|$]]|$1|H|3|I|5|6|7|Y|8|@]|9|@]|A|$]]|$1|J|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|K|$L|$5|M|N|O|A|$P|Q|R|-4]]]]

<img src="https://i.stack.imgur.com/oJ3wL.png" alt="enter image description here">

Set this autoresizing mask to your inner view.

blocks|key|317377|text|我将使用：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|317378|child.center+=+CGPointMake(parent.bounds.height+/+2,+parent.bounds.width+/+2)|code-block|syntax|javascript|317379|这是简单、简短和甜蜜的。如果你使用@Hejazi上面的答案，并且parent.center设置为(0,0)以外的任何值，你的子视图将不会居中！|offset|length|style|CODE|317380|entityMap^0|0|0|W|D|1C|5|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@$I|R|J|S|K|L]|$I|T|J|U|K|L]]|9|@]|A|$]]|$1|M|3|-4|5|6|7|V|8|@]|9|@]|A|$]]]|N|$]]

I would use:

<pre><code>child.center = CGPointMake(parent.bounds.height / 2, parent.bounds.width / 2)
</code></pre>

This is simple, short, and sweet. If you use @Hejazi's answer above and <code>parent.center</code> is set to anything other than <code>(0,0)</code> your subview will not be centered!

blocks|key|317408|text|我将使用：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|317409|self.childView.center+=+CGPointMake(CGRectGetMidX(self.parentView.bounds),
++++++++++++++++++++++++++++++++++++CGRectGetMidY(self.parentView.bounds));|code-block|syntax|javascript|317410|我喜欢使用CGRect选项...|offset|length|style|CODE|317411|SWIFT+3：|317412|self.childView.center+=+CGPoint(x:+self.parentView.bounds.midX,
++++++++++++++++++++++++++++++++++++++++y:+self.parentView.bounds.midY);|317413|entityMap^0|0|0|5|6|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@$I|V|J|W|K|L]]|9|@]|A|$]]|$1|M|3|N|5|6|7|X|8|@]|9|@]|A|$]]|$1|O|3|P|5|D|7|Y|8|@]|9|@]|A|$E|F]]|$1|Q|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|R|$]]

I would use:

<pre><code>self.childView.center = CGPointMake(CGRectGetMidX(self.parentView.bounds),
 CGRectGetMidY(self.parentView.bounds));
</code></pre>

I like to use the <code>CGRect</code> options...

SWIFT 3:

<pre><code>self.childView.center = CGPoint(x: self.parentView.bounds.midX,
 y: self.parentView.bounds.midY);
</code></pre>

blocks|key|317518|text|另一种解决方案是使用autoCenterInSuperview的PureLayout。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|317519|//+...
UIView+*innerView+=+[UIView+newAutoLayoutView];
innerView.backgroundColor+=+[UIColor+greenColor];
[innerView+autoSetDimensionsToSize:CGSizeMake(100,+30)];

[outerview+addSubview:innerView];

[innerView+autoCenterInSuperview];|code-block|syntax|javascript|317520|这是它看起来的样子：|317521|​|317522|📷|atomic|317523|317524|entityMap|0|LINK|mutability|MUTABLE|url|https://github.com/smileyborg/PureLayout|1|IMAGE|IMMUTABLE|imageUrl|https://ask.qcloudimg.com/http-save/yehe-900000/0cad57967fcf217fb550e022d1ea7803.png|imageAlt^0|A|L|W|A|0|0|0|0|0|0|1|1|0|0^^$0|@$1|2|3|4|5|6|7|16|8|@$9|17|A|18|B|C]]|D|@$9|19|A|1A|1|1B]]|E|$]]|$1|F|3|G|5|H|7|1C|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|1D|8|@]|D|@]|E|$]]|$1|M|3|N|5|6|7|1E|8|@]|D|@]|E|$]]|$1|O|3|P|5|Q|7|1F|8|@]|D|@$9|1G|A|1H|1|1I]]|E|$]]|$1|R|3|N|5|6|7|1J|8|@]|D|@]|E|$]]|$1|S|3|-4|5|6|7|1K|8|@]|D|@]|E|$]]]|T|$U|$5|V|W|X|E|$Y|Z]]|10|$5|11|W|12|E|$13|14|15|-4]]]]

Another solution with <a href="https://github.com/smileyborg/PureLayout" rel="nofollow noreferrer">PureLayout</a> using <code>autoCenterInSuperview</code>.

<pre><code>// ...
UIView *innerView = [UIView newAutoLayoutView];
innerView.backgroundColor = [UIColor greenColor];
[innerView autoSetDimensionsToSize:CGSizeMake(100, 30)];

[outerview addSubview:innerView];

[innerView autoCenterInSuperview];
</code></pre>

This is it how it looks like:

<img src="https://i.stack.imgur.com/M7dIN.png" alt="Center with PureLayout">

blocks|key|317767|text|在开始之前，让我们先提醒一下，原点是视图的左上角CGPoint。关于视图和父级，有一件重要的事情需要理解。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|317768|让我们看一下这个简单的代码，一个视图控制器，它在视图中添加了一个黑色方块：|317769|class+ViewController:+UIViewController+{

++++override+func+viewDidLoad()+{
++++++++super.viewDidLoad()
++++++++//+Do+any+additional+setup+after+loading+the+view,+typically+from+a+nib.
++++++++createDummyView()
++++++++super.view.backgroundColor+=+UIColor.cyanColor();
++++}

++++func+createDummyView(){
++++++++var+subView+=+UIView(frame:+CGRect(x:+15,+y:+50,+width:+50+,+height:+50));
++++++++super.view.addSubview(subView);
++++++++view.backgroundColor+=+UIColor.blackColor()
++++}

}|code-block|syntax|javascript|317770|这将创建此视图:黑色矩形原点和中心与其父对象的坐标相同|317771|​|317772|📷|atomic|317773|317774|现在，让我们尝试添加subView的另一个SubSubView，并为subSubview提供与subView相同的来源，但使subSubView成为subView的子视图|317775|我们将添加以下代码：|317776|var+subSubView+=+UIView();
subSubView.frame.origin+=+subView.frame.origin;
subSubView.frame.size+=+CGSizeMake(20,+20);
subSubView.backgroundColor+=+UIColor.purpleColor()
subView.addSubview(subSubView)|317777|这就是结果：|317778|317779|317780|317781|因为有这一行：|317782|subSubView.frame.origin+=+subView.frame.origin;|317783|您希望紫色矩形的原点与它的父矩形(黑色矩形)相同，但它位于它的下方，这是为什么？因为当您将一个视图添加到另一个视图时，subView框架"world“现在是它的父边界矩形，如果您有一个视图，它在主屏幕上的原点是它的所有子视图的坐标(15,15)，则左上角将是(0,0)|317784|这就是为什么你总是需要通过它的绑定矩形来引用父元素的原因，这就是它的subViews的“世界”，让我们将这一行修改为：|317785|subSubView.frame.origin+=+subView.bounds.origin;|317786|看看这个魔术，subSubview现在恰好位于它的父原点：|317787|317788|317789|317790|所以，你喜欢“好吧，我只是想把我的观点放在我父母的观点的中心，这有什么大不了的？”好吧，这没什么大不了的，你只需要将父中心点从它的帧“翻译”到父中心点的边界中心就可以了：|317791|subSubView.center+=+subView.convertPoint(subView.center,+fromView:+subSubView);|317792|你实际上是在告诉他“以父母为中心，并将其转换为subSubView世界”。|317793|你会得到这样的结果：|317794|317795|317796|317797|entityMap|0|IMAGE|mutability|IMMUTABLE|imageUrl|https://ask.qcloudimg.com/http-save/yehe-900000/0f775690b2176f388e97871105bda3fb.png|imageAlt|1|https://ask.qcloudimg.com/http-save/yehe-900000/351a8be11faef2857bc6f83886767824.png|2|https://ask.qcloudimg.com/http-save/yehe-900000/ee6824484932ea5a31ad594d29f99ffa.png|3|https://ask.qcloudimg.com/http-save/yehe-900000/78cfbda199ce198e3aa7e648129c2fc1.png^0|O|7|0|0|0|0|0|0|1|0|0|0|0|0|0|0|0|0|1|1|0|0|0|0|0|0|0|0|0|0|1|2|0|0|0|0|0|0|0|0|1|3|0|0^^$0|@$1|2|3|4|5|6|7|2A|8|@$9|2B|A|2C|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|2D|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|2E|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|2F|8|@]|D|@]|E|$]]|$1|O|3|P|5|6|7|2G|8|@]|D|@]|E|$]]|$1|Q|3|R|5|S|7|2H|8|@]|D|@$9|2I|A|2J|1|2K]]|E|$]]|$1|T|3|P|5|6|7|2L|8|@]|D|@]|E|$]]|$1|U|3|V|5|6|7|2M|8|@]|D|@]|E|$]]|$1|W|3|X|5|6|7|2N|8|@]|D|@]|E|$]]|$1|Y|3|Z|5|J|7|2O|8|@]|D|@]|E|$K|L]]|$1|10|3|11|5|6|7|2P|8|@]|D|@]|E|$]]|$1|12|3|P|5|6|7|2Q|8|@]|D|@]|E|$]]|$1|13|3|R|5|S|7|2R|8|@]|D|@$9|2S|A|2T|1|2U]]|E|$]]|$1|14|3|P|5|6|7|2V|8|@]|D|@]|E|$]]|$1|15|3|16|5|6|7|2W|8|@]|D|@]|E|$]]|$1|17|3|18|5|J|7|2X|8|@]|D|@]|E|$K|L]]|$1|19|3|1A|5|6|7|2Y|8|@]|D|@]|E|$]]|$1|1B|3|1C|5|6|7|2Z|8|@]|D|@]|E|$]]|$1|1D|3|1E|5|J|7|30|8|@]|D|@]|E|$K|L]]|$1|1F|3|1G|5|6|7|31|8|@]|D|@]|E|$]]|$1|1H|3|P|5|6|7|32|8|@]|D|@]|E|$]]|$1|1I|3|R|5|S|7|33|8|@]|D|@$9|34|A|35|1|36]]|E|$]]|$1|1J|3|P|5|6|7|37|8|@]|D|@]|E|$]]|$1|1K|3|1L|5|6|7|38|8|@]|D|@]|E|$]]|$1|1M|3|1N|5|J|7|39|8|@]|D|@]|E|$K|L]]|$1|1O|3|1P|5|6|7|3A|8|@]|D|@]|E|$]]|$1|1Q|3|1R|5|6|7|3B|8|@]|D|@]|E|$]]|$1|1S|3|P|5|6|7|3C|8|@]|D|@]|E|$]]|$1|1T|3|R|5|S|7|3D|8|@]|D|@$9|3E|A|3F|1|3G]]|E|$]]|$1|1U|3|P|5|6|7|3H|8|@]|D|@]|E|$]]|$1|1V|3|-4|5|6|7|3I|8|@]|D|@]|E|$]]]|1W|$1X|$5|1Y|1Z|20|E|$21|22|23|-4]]|24|$5|1Y|1Z|20|E|$21|25|23|-4]]|26|$5|1Y|1Z|20|E|$21|27|23|-4]]|28|$5|1Y|1Z|20|E|$21|29|23|-4]]]]

Before we'll begin, let's just remind that origin point is the Upper Left corner <code>CGPoint</code> of a view.
An important thing to understand about views and parents.

Lets take a look at this simple code, a view controller that adds to it's view a black square:

<pre><code>class ViewController: UIViewController {

 override func viewDidLoad() {
 super.viewDidLoad()
 // Do any additional setup after loading the view, typically from a nib.
 createDummyView()
 super.view.backgroundColor = UIColor.cyanColor();
 }

 func createDummyView(){
 var subView = UIView(frame: CGRect(x: 15, y: 50, width: 50 , height: 50));
 super.view.addSubview(subView);
 view.backgroundColor = UIColor.blackColor()
 }

}
</code></pre>

This will create this view:
the black rectangle origin and center does fit the same coordinates as it's parent

<a href="https://i.stack.imgur.com/kNM0f.png" rel="noreferrer"><img src="https://i.stack.imgur.com/kNM0f.png" alt="enter image description here"></a>

Now let's try to add subView another SubSubView, and giving subSubview same origin as subView, but make subSubView a child view of subView

We'll add this code:

<pre><code>var subSubView = UIView();
subSubView.frame.origin = subView.frame.origin;
subSubView.frame.size = CGSizeMake(20, 20);
subSubView.backgroundColor = UIColor.purpleColor()
subView.addSubview(subSubView)
</code></pre>

And this is the result:

<a href="https://i.stack.imgur.com/viHzv.png" rel="noreferrer"><img src="https://i.stack.imgur.com/viHzv.png" alt="enter image description here"></a>

Because of this line:

<pre><code>subSubView.frame.origin = subView.frame.origin;
</code></pre>

You expect for the purple rectangle's origin to be same as it's parent (the black rectangle) but it goes under it, and why is that?
Because when you add a view to another view, the subView frame "world" is now it's parent BOUND RECTANGLE, if you have a view that it's origin on the main screen is at coords (15,15) for all it's sub views, the upper left corner will be (0,0)

This is why you need to always refer to a parent by it's bound rectangle, which is the "world" of it's subViews, lets fix this line to:

<pre><code>subSubView.frame.origin = subView.bounds.origin;
</code></pre>

And see the magic, the subSubview is now located exactly in it's parent origin:

<a href="https://i.stack.imgur.com/fpudG.png" rel="noreferrer"><img src="https://i.stack.imgur.com/fpudG.png" alt="enter image description here"></a>

So, you like "ok I only wanted to center my view by my parents view, what's the big deal?" 
well, it isn't big deal, you just need to "translate" the parent Center point which is taken from it's frame to parent's bounds center
by doing this:

<pre><code>subSubView.center = subView.convertPoint(subView.center, fromView: subSubView);
</code></pre>

You're actually telling him "take parents view center, and convert it into subSubView world".

And you'll get this result:

<a href="https://i.stack.imgur.com/XDbSd.png" rel="noreferrer"><img src="https://i.stack.imgur.com/XDbSd.png" alt="enter image description here"></a>

blocks|key|317810|text|最简单的方法：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|317811|child.center+=+parent.center|code-block|syntax|javascript|317812|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

The easiest way:

<pre><code>child.center = parent.center
</code></pre>

blocks|key|317887|text|通过IOS9，您可以使用布局锚点应用编程接口。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|317888|代码将如下所示：|317889|childview.centerXAnchor.constraintEqualToAnchor(parentView.centerXAnchor).active+=+true
childview.centerYAnchor.constraintEqualToAnchor(parentView.centerYAnchor).active+=+true|code-block|syntax|javascript|317890|与CGPointMake或CGRect相比，这种方法的优点是您可以将视图的中心设置为常量，但是使用这种技术，您可以设置两个视图之间的关系，该关系将永远保持不变，而不管parentview如何更改。|offset|length|style|CODE|317891|在执行此操作之前，只需确保：|317892|++++++++self.view.addSubview(parentView)
++++++++self.view.addSubView(chidview)|317893|并将每个视图的translatesAutoresizingMaskIntoConstraints设置为false。|317894|这将防止崩溃和AutoLayout的干扰。|317895|entityMap^0|0|0|0|1|B|D|6|2B|A|0|0|0|7|15|0|0^^$0|@$1|2|3|4|5|6|7|Y|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|Z|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|10|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|11|8|@$K|12|L|13|M|N]|$K|14|L|15|M|N]|$K|16|L|17|M|N]]|9|@]|A|$]]|$1|O|3|P|5|6|7|18|8|@]|9|@]|A|$]]|$1|Q|3|R|5|F|7|19|8|@]|9|@]|A|$G|H]]|$1|S|3|T|5|6|7|1A|8|@$K|1B|L|1C|M|N]]|9|@]|A|$]]|$1|U|3|V|5|6|7|1D|8|@]|9|@]|A|$]]|$1|W|3|-4|5|6|7|1E|8|@]|9|@]|A|$]]]|X|$]]

With IOS9 you can use the layout anchor API.

The code would look like this:

<pre><code>childview.centerXAnchor.constraintEqualToAnchor(parentView.centerXAnchor).active = true
childview.centerYAnchor.constraintEqualToAnchor(parentView.centerYAnchor).active = true
</code></pre>

The advantage of this over <code>CGPointMake</code> or <code>CGRect</code> is that with those methods you are setting the center of the view to a constant but with this technique you are setting a relationship between the two views that will hold forever, no matter how the <code>parentview</code> changes.

Just be sure before you do this to do:

<pre><code> self.view.addSubview(parentView)
 self.view.addSubView(chidview)
</code></pre>

and to set the <code>translatesAutoresizingMaskIntoConstraints</code> for each view to false.

This will prevent crashing and AutoLayout from interfering.

blocks|key|534813|text|您可以使用|type|unstyled|depth|inlineStyleRanges|entityRanges|data|534814|yourView.center+=+CGPointMake(CGRectGetMidX(superview.bounds),+CGRectGetMidY(superview.bounds))|code-block|syntax|javascript|534815|在Swift+3.0中|534816|yourView.center+=+CGPoint(x:+superview.bounds.midX,+y:+superview.bounds.midY)|534817|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

You can use 

<pre><code>yourView.center = CGPointMake(CGRectGetMidX(superview.bounds), CGRectGetMidY(superview.bounds))
</code></pre>

And In Swift 3.0 

<pre><code>yourView.center = CGPoint(x: superview.bounds.midX, y: superview.bounds.midY)
</code></pre>

blocks|key|534866|text|在c#或Xamarin.ios中，我们可以这样使用|type|unstyled|depth|inlineStyleRanges|entityRanges|data|534867|imageView.Center+=新的CGPoint(tempView.Frame.Size.Width+/+2，tempView.Frame.Size.Height+/+2)；|534868|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

In c# or Xamarin.ios, we can use like this

imageView.Center = new CGPoint(tempView.Frame.Size.Width / 2,
 tempView.Frame.Size.Height / 2);

blocks|key|534898|text|func+callAlertView()+{

++++UIView.animate(withDuration:+0,+animations:+{
++++++++let+H+=+self.view.frame.height+*+0.4
++++++++let+W+=+self.view.frame.width+*+0.9
++++++++let+X+=+self.view.bounds.midX+-+(W/2)
++++++++let+Y+=+self.view.bounds.midY+-+(H/2)
++++++++self.alertView.frame+=+CGRect(x:X,+y:+Y,+width:+W,+height:+H)
++++++++self.alertView.layer.borderWidth+=+1
++++++++self.alertView.layer.borderColor+=+UIColor.red.cgColor
++++++++self.alertView.layer.cornerRadius+=+16
++++++++self.alertView.layer.masksToBounds+=+true
++++++++self.view.addSubview(self.alertView)

++++})


}//+calculation+works+adjust+H+and+W+according+to+your+requirement|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|534899|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>func callAlertView() {

 UIView.animate(withDuration: 0, animations: {
 let H = self.view.frame.height * 0.4
 let W = self.view.frame.width * 0.9
 let X = self.view.bounds.midX - (W/2)
 let Y = self.view.bounds.midY - (H/2)
 self.alertView.frame = CGRect(x:X, y: Y, width: W, height: H)
 self.alertView.layer.borderWidth = 1
 self.alertView.layer.borderColor = UIColor.red.cgColor
 self.alertView.layer.cornerRadius = 16
 self.alertView.layer.masksToBounds = true
 self.view.addSubview(self.alertView)

 })


}// calculation works adjust H and W according to your requirement
</code></pre>

blocks|key|318048|text|这对我很有效|type|unstyled|depth|inlineStyleRanges|entityRanges|data|318049|childView.centerXAnchor.constraint(equalTo:+parentView.centerXAnchor).isActive+=+true
childView.centerYAnchor.constraint(equalTo:+parentView.centerYAnchor).isActive+=+true|code-block|syntax|javascript|318050|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

This worked for me
<pre><code>childView.centerXAnchor.constraint(equalTo: parentView.centerXAnchor).isActive = true
childView.centerYAnchor.constraint(equalTo: parentView.centerYAnchor).isActive = true
</code></pre>

I have a <code>UIView</code> inside a <code>UIView</code>m and I want the inner <code>UIView</code> to be always centered inside the outer one, without it having to resize the width and height.

I've set the struts and springs so that it's on top/left/right/bottom without setting the resize. But it still doesn't center. Any idea?

How to center a subview of UIView

Objective-C

Xamarin

Swift

我在UIViewm中有一个UIView，我希望内部的UIView总是居中在外部的中间，而不需要调整宽度和高度。我已经设置了支撑杆和弹簧，使其位于顶部/左侧/右侧/底部，而不设置调整大小。但它仍然不在中心。有什么想法吗？

问如何使UIView的子视图居中
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