UIScrollView与自动布局混合方法? [英] UIScrollView with autolayout mixed approach?

问题描述

我正在尝试使用苹果开发人员解决方案

我不明白，如果您只是想在滚动视图中堆叠视图，为什么需要约束.我尝试了您的代码，但滚动效果却不如您所说，但是我认为是由于您将UIScrollView用作视图控制器的主视图而引起的，您是否有特定原因想要这样做? /p>

我更改了代码，而是将UIScrollView添加到普通的UIView中，并且它可以按预期完美运行，而无需使用任何复杂的约束.只需记住使用UIScrollView *scrollView;

在顶部定义滚动视图即可.

- (void)viewDidLoad {
    [super viewDidLoad];

    scrollView = [[UIScrollView alloc] initWithFrame:self.view.bounds];
    [self.view addSubview:scrollView];

    CGFloat w = self.view.frame.size.width;
    CGFloat h = self.view.frame.size.height;

    contentView = [[UIView alloc] initWithFrame:CGRectMake(0,0, w, h*3)];
    [scrollView addSubview:contentView];

    v1 =[[UIView alloc] initWithFrame:CGRectMake(0,0, w, h)];
    v2 =[[UIView alloc] initWithFrame:CGRectMake(0,h, w, h)];
    v3 =[[UIView alloc] initWithFrame:CGRectMake(0,h*2, w, h)];

    v1.backgroundColor = [UIColor redColor];
    v2.backgroundColor = [UIColor greenColor];
    v3.backgroundColor = [UIColor blueColor];

    [contentView addSubview:v1];
    [contentView addSubview:v2];
    [contentView addSubview:v3];

    scrollView.contentSize = contentView.bounds.size;
}

I am trying to work an example code thats using the 'mixed approach' mention on apple dev link:

I am trying to stack 3 views vertically in UIScrollView. In below example the UIScrollView shows the red view on load but does not scroll as expected. I can scroll a little bit to see the green view below the red view - but the scroll view springs back up and does not scroll to the green view or view below it(blue view). I understand I need a constraint I tried to add one between view 1 & 2 so that view2.top = view1.bottom ,but seems I am missing something.

Also I noticed the content size of the scrollview is zero ( in viewDidAppear method).

Any tips on what I am missing or help on how to get this mixed approach working would be of great!!

    - (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.


    UIScrollView* scrollView = ((UIScrollView*)self.view);

    scrollView.translatesAutoresizingMaskIntoConstraints = NO;

    CGFloat w = self.view.frame.size.width;
    CGFloat h = self.view.frame.size.height;

    contentView = [[UIView alloc] initWithFrame:CGRectMake(0,0, w, h*3)];

    [scrollView addSubview:contentView];


    v1 =[[UIView alloc] initWithFrame:CGRectMake(0,0, w, h)];
    v2 =[[UIView alloc] initWithFrame:CGRectMake(0,h, w, h)];
    v3 =[[UIView alloc] initWithFrame:CGRectMake(0,h*2, w, h)];

    v1.backgroundColor = [UIColor redColor];
    v2.backgroundColor = [UIColor greenColor];
    v3.backgroundColor = [UIColor blueColor];


    [contentView addSubview:v1];
    [contentView addSubview:v2];
    [contentView addSubview:v3];

    NSLayoutConstraint *myConstraint =[NSLayoutConstraint
                                       constraintWithItem:v1
                                       attribute:NSLayoutAttributeBottom
                                       relatedBy:NSLayoutRelationEqual
                                       toItem:v2
                                       attribute:NSLayoutAttributeTop
                                       multiplier:1.0
                                       constant:0];

    [contentView addConstraint:myConstraint];

    scrollView.contentSize = contentView.bounds.size;

}

解决方案

I dont understand why you would need a constraint if you are just trying to stack views in a scroll view. I tried your code and it does not scroll well like you said, but I think it is being caused because you are using a UIScrollView as the main view for the view controller, is there a specific reason you want to do it like this?

I changed the code to instead add a UIScrollView to the normal UIView and it works perfectly as expected without using any complicated constraints. Just remember to define the scroll view at the top by using UIScrollView *scrollView;

- (void)viewDidLoad {
    [super viewDidLoad];

    scrollView = [[UIScrollView alloc] initWithFrame:self.view.bounds];
    [self.view addSubview:scrollView];

    CGFloat w = self.view.frame.size.width;
    CGFloat h = self.view.frame.size.height;

    contentView = [[UIView alloc] initWithFrame:CGRectMake(0,0, w, h*3)];
    [scrollView addSubview:contentView];

    v1 =[[UIView alloc] initWithFrame:CGRectMake(0,0, w, h)];
    v2 =[[UIView alloc] initWithFrame:CGRectMake(0,h, w, h)];
    v3 =[[UIView alloc] initWithFrame:CGRectMake(0,h*2, w, h)];

    v1.backgroundColor = [UIColor redColor];
    v2.backgroundColor = [UIColor greenColor];
    v3.backgroundColor = [UIColor blueColor];

    [contentView addSubview:v1];
    [contentView addSubview:v2];
    [contentView addSubview:v3];

    scrollView.contentSize = contentView.bounds.size;
}

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