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我是使用 Autolayouts 的新手，即使这是我的第一次尝试。无论我用它做什么，我都会以白屏结束。这是我的尝试。

我有一个UIView，让我说一个parentView框架(60, 154, 200, 200)。它是一个子视图self.view。

然后我有一个动态视图，比如dynamicView框架(0, 0, 260, 100)和一个label框架(15, 25, 230, 50)，它是一个子视图dynamicView。

当我将dynamicViewas 子视图添加到 时parentView，它超出了parentView' 范围。所以，我想调整 thedynamicView及其 child( label) 的大小，使其位置位于 the 的中心parentView并且dynamicView在parentView's 的范围内。

我的第一次尝试是设置clipsToBounds，它在 Xcode5、iOS7 中不起作用。所以下一个选择是使用NSLayoutConstraint. 我对此一无所知。我欢迎你的想法。

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2 回答 2

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i'll just address the dyanmicView being part of the parentView issue, then let you go from there

first: if you are creating the view dynamically, then you're good to go, but if you've created it from storyboard, you'd have to detach it from it's parent then reattach it.. that's how you get rid of it's previous NSConstraints (that usually the storyboard introduces) that may conflict with your new ones.

you also gotta set it's setTranslatesAutoresizingMaskIntoConstraints to NO b/c that also can interfere with your nsconstraints.

I usually do those last two steps like so, using mapObjectsUsingBlock to make the whole tedious process of creating constraints a bit more pleasant and natural:

    [@[view_1, view_2, /../, view_n] mapObjectsApplyingBlock:^(UIView *view) {
        [view removeFromSuperview];
        [view setTranslatesAutoresizingMaskIntoConstraints:NO];
        [view setHidden:NO];
        [superView addSubview:view];
    }];

then before applying nsconstraints, you gotta make sure that the view you want the constraints to apply to is already attached to it's parent:

[parentView addSubview:dynamicView];

then you want to create a bindings dictionary:

NSDictionary *buttonBindingsDictionary = @{ @"parentView" : parentView,
                                            @"dynamicView" : dynamicView};

then you want to add the constraints using the visual format language.. I also use mapObjectsUsingBlock here (i'll explain each constraint in english):

NSArray *buttonConstraints = [@[@"V:|-[dynamicView(>=200)]-|",
                                @"|-[dynamicView(>=260)]-|",
                                ] mapObjectsUsingBlock:^id(NSString *formatString, NSUInteger idx){
    return [NSLayoutConstraint constraintsWithVisualFormat:formatString options:0 metrics:nil views:buttonBindingsDictionary];
}];

V:|-[dynamicView(>=200)]-| means that vertically speaking.. the upper and lower distance between dynamicView and it's parent should be equal.. also dynamicView's height should be no less than 200

|-[dynamicView(>=260)]-| means that horizontally speaking.. the left and right distance between dyanmicview and it's parent should be equal.. also dyanmicView's width should be no less than 260

note: you can do the math yourself and set exactly how much the left/right/bottom/top distance between dyanicView and it's parent.. this is just simpler.. but sometimes nsconstraints messes up and I gotta do it myself.

in that case it would look something like this where x is the distance you came up with:

V:|-x-[dynamicView(>=200)]-x-|
|-x-[dynamicView(>=260)]-x-|

then you gotta add the constraints to the parent view:

[parentView addConstraints:[buttonConstraints flattenArray]];

notice here i used flatten array, again that's a method from my library b/c i want to feed it a one level array, not an array of arrays.

and you're good to go!

note: i know that this may not work perfectly.. but it gives you the idea of what to do + some helper files. It takes some practice, and you should look at some of the tutorials for sure.. i suggest you start with nsconstraints using storyboard (you can select a view.. then go editor>pin>.. then chose something.. get some immediate visual feedback.. also you can simulate what your views will look like in 3.5" displays vs 4.0" displays immediately on the storyboard by selecting the view controller, then going to attributes inspector and selecting different sizes under simulated metrics)

take your time bud, but one thing for sure: once you go nsconstraints you will never look back! it's totally worth it!

p.s. you can also animate views using nsconstraints as well.. just in case you were wondering.

于 2013-10-08T09:59:02.237 回答
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自动布局约束是您尝试实现的最佳方法。当您在 IB 中选中 Use Autolayout 选项时，会自动添加自动布局约束。

查看本教程，其中详细介绍了 iOS6 中的自动布局 http://www.raywenderlich.com/20881/beginning-auto-layout-part-1-of-2

然后您可以查看此链接以获取 iOS7 中更新的自动布局 http://www.doubleencore.com/2013/09/auto-layout-updates-in-ios-7/

于 2013-10-08T09:43:45.093 回答