ios - 使用自动布局设置此UI

我正在尝试使用自动版面设置视图，以便在视图更改大小时可以很好地设置动画效果...

情况是...

我有一个UIView和一个名为animView的子视图。 animView在视图框架之外开始。
随着视图的增大(变高)，animView以相同的速率向下移动。
当animView从视图顶部起10点时(即@“V:| -10- [animView]”)，它停止并“粘在”该点。

即像这样的东西...

最佳答案

这有效(Dropbox share for the project):

诀窍是使用不可见的UIView作为间隔对象。您称为animView的视图就是这样设置的。因为我在IB中对此进行了部分设置，所以它仍然会引起一些问题，但是您会看到它可以按需运行。

@implementation AnimView {

    UIView * _innerBox;
    UIView * _spacer;
}

然后从- setUpEverything或initWithCoder:调用方法initWithFrame:。

- (void) setUpEverything {


    // Because I set this up in IB with AutoLayout off, I think it
    // still needs this. Won't work without it
    self.translatesAutoresizingMaskIntoConstraints = YES;

    // Otherwise you will see the box outside of animView
    self.clipsToBounds = YES;

    _innerBox = [[UIView alloc] init];
    _innerBox.backgroundColor = [UIColor blackColor];
    _spacer = [[UIView alloc] init];
    _spacer.backgroundColor = [UIColor clearColor];
    _innerBox.translatesAutoresizingMaskIntoConstraints = NO;
    _spacer.translatesAutoresizingMaskIntoConstraints = NO;
    [self addSubview:_innerBox];
    [self addSubview:_spacer];

    // Give _innerBox and _spacer some dimensions to prevent ambiguity

    NSLayoutConstraint *i02 = [NSLayoutConstraint constraintWithItem:_innerBox attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationEqual toItem:nil attribute:0 multiplier:1.0f constant:50.0f];
    NSLayoutConstraint *i03 = [NSLayoutConstraint constraintWithItem:_innerBox attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:nil attribute:0 multiplier:1.0f constant:50.0f];
    NSLayoutConstraint *s02 = [NSLayoutConstraint constraintWithItem:_spacer attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationEqual toItem:nil attribute:0 multiplier:1.0f constant:50.0f];

    // Center both views
    NSLayoutConstraint *i05 = [NSLayoutConstraint constraintWithItem:_innerBox attribute:NSLayoutAttributeCenterX relatedBy:NSLayoutRelationEqual toItem:self attribute:NSLayoutAttributeCenterX multiplier:1.0f constant:0.0f];
    NSLayoutConstraint *s04 = [NSLayoutConstraint constraintWithItem:_spacer attribute:NSLayoutAttributeCenterX relatedBy:NSLayoutRelationEqual toItem:self attribute:NSLayoutAttributeCenterX multiplier:1.0f constant:0.0f];

    // Set the top of _innerBox 10.0 points from the top of the superview with a low priority
    NSLayoutConstraint *i01 = [NSLayoutConstraint constraintWithItem:_innerBox attribute:NSLayoutAttributeTop relatedBy:NSLayoutRelationEqual toItem:self attribute:NSLayoutAttributeTop multiplier:1.0f constant:10.0f];
    i01.priority = 250;

    // Pin the spacer to the bottom of _innerBox;
    NSLayoutConstraint *i04 = [NSLayoutConstraint constraintWithItem:_innerBox attribute:NSLayoutAttributeBottom relatedBy:NSLayoutRelationEqual toItem:_spacer attribute:NSLayoutAttributeTop multiplier:1.0f constant:0.0f];

    // Pin the spacer's bottom to the bottom of the superview
    NSLayoutConstraint *s01 = [NSLayoutConstraint constraintWithItem:_spacer attribute:NSLayoutAttributeBottom relatedBy:NSLayoutRelationEqual toItem:self attribute:NSLayoutAttributeBottom multiplier:1.0f constant:0.0f];

    // Stretch the spacer out as needed
    NSLayoutConstraint *s03 = [NSLayoutConstraint constraintWithItem:_spacer attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationGreaterThanOrEqual toItem:nil attribute:0 multiplier:1.0f constant:80.0f];


    [self addConstraints:@[i01,i02,i03,i04,i05,s01,s02,s03,s04]];

}