如何使用autolayout使视图浮动在滚动视图上

问题描述

在有以下声明：

任何人都有任何想法吗？

Anyone have any ideas?

推荐答案

我做了一些游戏，我有一个各种工作的例子。

I did some playing around and I have a working example of sorts.

视图不会滚动，它会放在顶部，其高度是scrollview hight和任意值之间的差值。

The view does not scroll, it gets put at the top, with a height that is the difference between the scrollview hight and an arbitrary value.

// in viewDidLoad

UIIView *myView = [[UIView alloc] init];
[self.scrollView addSubview:myView];
myView.translatesAutoresizingMaskIntoConstraints = NO;

NSLayoutConstraint *constraint = [NSLayoutConstraint constraintWithItem:self.mapView
    attribute:NSLayoutAttributeTop
    relatedBy:(NSLayoutRelationEqual)
       toItem:self.containerView
    attribute:(NSLayoutAttributeTop)
   multiplier:1.0
     constant:0];
[self.view addConstraint:constraint];


// Give my view some intrinsic size
NSDictionary *dict = NSDictionaryOfVariableBindings(myView);
NSArray *constraints = [NSLayoutConstraint constraintsWithVisualFormat:@"|[myView]|"
                                                               options:(NSLayoutFormatAlignAllBaseline)
                                                               metrics:nil
                                                                 views:dict];
[self.view addConstraints:constraints];

// In view did appear

// calc height from height of scroll view - this is needs work
float height = -self.scrollView.frame.size.height + 250;

NSLayoutConstraint *constraint = [NSLayoutConstraint constraintWithItem:self.mapView                attribute:NSLayoutAttributeHeight
    relatedBy:(NSLayoutRelationEqual)
       toItem:self.containerView
    attribute:(NSLayoutAttributeHeight)
       multiplier:1.0
     constant:offset];
[self.view addConstraint:constraint];

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