iOS自动布局:适合超级视图宽度的相等空间

Question

可能重复:
Autolayout均匀间距

我正在尝试创建一个带按钮的可滚动条(类似于a UISegmentedControl).超级视图是一个UIScrollView.一旦按钮不适合滚动视图,滚动视图应该是可滚动的.到目前为止,几乎一切正常:

有很多按钮(向右滚动):

没有那么多按钮:

现在,我的目标是,如果所有按钮都有空间,它们应该平均分布在整个320px视图中.如何为按钮之间的空间定义约束？

现在,我正在使用以下约束(self是a UIScrollView):

UIView *firstButton = self.buttons[0];

[self.buttonConstraints addObjectsFromArray:[NSLayoutConstraint constraintsWithVisualFormat:@"|-(5)-[firstButton]" options:0 metrics:nil views:NSDictionaryOfVariableBindings(firstButton)]];

UIView *lastButton = [self.buttons lastObject];

[self.buttonConstraints addObjectsFromArray:[NSLayoutConstraint constraintsWithVisualFormat:@"[lastButton]-(5)-|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(lastButton)]];

UIView *previousView = nil;

for (UIView *view in self.buttons) {
    if (previousView) {
        [self.buttonConstraints addObjectsFromArray:[NSLayoutConstraint constraintsWithVisualFormat:@"[previousView]-(5)-[view]" options:0 metrics:nil views:NSDictionaryOfVariableBindings(previousView, view)]];
    }
    previousView = view;
}

如果我将superview的类型更改UIScrollView为a UIView,我会得到以下结果,仍然不是我想要的,但至少它会查找将它与右边缘联系起来的最后一个按钮的约束(有意义,这不是滚动视图不会发生,因为内容大小是自动设置的):

有任何想法吗？

Answer 1

- (void) viewWillLayoutSubviews {
    // UIButton *button1, *button2, *button3, *button 4 ;
    // NSMutableArray *constraintsForButtons ;

    float unusedHorizontalSpace = self.view.bounds.size.width - button1.intrinsicContentSize.width - button2.intrinsicContentSize.width - button3.intrinsicContentSize.width - button4.intrinsicContentSize.width ;
    NSNumber* spaceBetweenEachButton=  [NSNumber numberWithFloat: unusedHorizontalSpace / 5 ] ;

    [self.view removeConstraints:constraintsForButtons] ;
    [constraintsForButtons removeAllObjects] ;
    [constraintsForButtons addObjectsFromArray: [NSLayoutConstraint constraintsWithVisualFormat: @"H:|-(space)-[button1]-(space)-[button2]-(space)-[button3]-(space)-[button4]-(space)-|"
                                                                                        options: NSLayoutFormatAlignAllCenterY
                                                                                        metrics: @{@"space":spaceBetweenEachButton}
                                                                                          views: NSDictionaryOfVariableBindings(button1,button2,button3,button4) ] ] ;
    [constraintsForButtons addObjectsFromArray: [NSLayoutConstraint constraintsWithVisualFormat: @"V:|[button1]"
                                                                                        options: 0
                                                                                        metrics: nil
                                                                                          views: NSDictionaryOfVariableBindings(button1) ] ] ;
    [self.view addConstraints:constraintsForButtons] ;
}

这不像你的那么漂亮,它假设有4个按钮,但它同样地将它们隔开.也就是说,按钮之间的空白区域都具有相同的宽度.这并不意味着button1和button2的NSLayoutAttributeLeading之间的距离与button2和button3之间的距离相同.