如何活动的指标定位到使用自动布局编程它的父的中心？ [英] How to position activity indicator to the center of its superview using Auto Layout programmatically?

问题描述

为什么以下code没有定位活动指示灯工作，它的父的中心：

Why the following code does not work for positioning activity indicator to the center of its superview:

UIActivityIndicatorView *activityIndicator = [[UIActivityIndicatorView alloc]
       initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhiteLarge];

[self.mysuperview addSubview:activityIndicator];
[activityIndicator addConstraints:[NSLayoutConstraint 
                   constraintsWithVisualFormat:@"|-(>=20)-[view(==100)]-(>=20)-|"
                   options:NSLayoutFormatAlignAllCenterX | NSLayoutFormatAlignAllCenterY
                   metrics:nil
                   views:@{@"view" : self.mysuperview}]];

活动指示灯在左上角某处定位时，绝对不是在中心

Activity indicator is positioned somewhere at the top left corner, definitely not in the centre.

==================
更新：
发现其解决：我创建指标后关闭自动尺寸调整的约束，然后将所有的解决方案，在这里给定的工作：

================== Update: FOUND SOLUTION: I have to turn off autoresizing constraints after creating indicator and then all solutions that where given work:

 [activityIndicator setTranslatesAutoresizingMaskIntoConstraints:NO];

我发现它被赋予@Vignesh的链接，所以我接受他/她的回答。

I found it on the link given by @Vignesh, so I accept his/her answer.

推荐答案

您可以试试这个，

 UIView *superview = self.mysuperview;
NSDictionary *variables = NSDictionaryOfVariableBindings(activityIndicator, superview);
NSArray *constraints =
[NSLayoutConstraint constraintsWithVisualFormat:@"V:[superview]-(<=1)-[activityIndicator]"
                                        options: NSLayoutFormatAlignAllCenterX
                                        metrics:nil
                                          views:variables];
[self.view addConstraints:constraints];

constraints =
[NSLayoutConstraint constraintsWithVisualFormat:@"H:[superview]-(<=1)-[activityIndicator]"
                                        options: NSLayoutFormatAlignAllCenterY
                                        metrics:nil
                                          views:variables];
[self.view addConstraints:constraints];

这里服用。

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