ios - 在自动版面环境中移动UIView

在我的视图控制器中，我有两个对象。 TopView和CustomScrollView。
我想将TopView放在顶部，并将CustomScrollView放在它们下面，所以我把它放在了这里:

// TOP VIEW LAYOUT

// horizontal

[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|    [_topView]|" options:NSLayoutFormatDirectionLeadingToTrailing metrics:nil views:NSDictionaryOfVariableBindings(_topView, self)]];
// vertical

 [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|[_topView(89)]" options:NSLayoutFormatDirectionLeadingToTrailing metrics:nil views:NSDictionaryOfVariableBindings(_topView, self)]];


// CUSTOMSCROLLVIEW

// horizontal

[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|[_customScrollVeiw]|" options:NSLayoutFormatDirectionLeadingToTrailing metrics:nil views:NSDictionaryOfVariableBindings(_customScrollVeiw, self)]];
// vertical

[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:[_topView]-(0)-[_customScrollVeiw]|" options:NSLayoutFormatDirectionLeadingToTrailing metrics:nil views:NSDictionaryOfVariableBindings(_customScrollVeiw, _topView,  self)]];

并且工作正常。

但是现在我想在CustomScrollView中滚动时移动Top视图，所以我创建了这个函数:

- (void) moveOnScroll: (CGPoint) offset contentSize: (CGSize) contentSize
{
float delta = offset.y - self.yPosition;
if (self.yPosition > offset.y) {
    if (labs(self.frame.origin.y) < self.frame.size.height/50 ){
        self.frame = CGRectMake(0, 0, self.frame.size.width, self.frame.size.height);
    }

    else if (self.frame.origin.y - delta < 0 && offset.y < (contentSize.height - self.screenHeight)){
        self.frame = CGRectMake(0, self.frame.origin.y - delta, self.frame.size.width, self.frame.size.height);
    }
    else{
        self.frame = CGRectMake(0, 0, self.frame.size.width, self.frame.size.height);
    }
}
else {
    if (self.frame.origin.y > (- self.frame.size.height  + self.labelHeight) && offset.y > 0){

        if (self.frame.origin.y - delta < (- self.frame.size.height  + self.labelHeight )) {
            self.frame = CGRectMake(0, (- self.frame.size.height  + self.labelHeight ), self.frame.size.width, self.frame.size.height);
        }
        else{
            self.frame = CGRectMake(0, self.frame.origin.y - delta , self.frame.size.width, self.frame.size.height);
        }
    }
}
self.yPosition = offset.y;
}

现在，当我滚动时，TopView隐藏了，但是CustomScrollView不再与TopView拥抱，它停留在他的位置并且不移动。 (V:[_ topView]-(0)-[_ customScrollVeiw] |)

如何解决这个问题？

最佳答案

将此约束保存在视图控制器中的某个位置

// vertical
NSArray *topViewContstraints = [NSLayoutConstraint constraintsWithVisualFormat:@"V:|[_topView(89)]" options:NSLayoutFormatDirectionLeadingToTrailing metrics:nil views:NSDictionaryOfVariableBindings(_topView, self)]
for (NSLayoutConstraint *constraint in topViewContstraints) {
    if (constraint.firstAttribute == NSLayoutAttributeHeight) {
        _topViewConstraint = constraint;
        break;
    }
}
[self.view addConstraints:topViewContstraints];

然后通过保存的约束更改顶视图的y位置:

_topViewConstraint.constant = yOffset;

其中yOffset是您的自定义方法中的计算值。

哦，您将希望对此更改进行动画处理:

[UIView animateWithDuration:0.3 animations:^{
         [_topView layoutIfNeeded];
}];

关于ios - 在自动版面环境中移动UIView，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/21524394/