如何以编程方式在 UIScrollView 中使用 AutoLayout 设置子视图?

问题描述

我正在使用自动布局以编程方式创建带有 UiScrollview 和 UIPagectontrol 的应用程序，用于

I am creating app with UiScrollview and UIPagectontrol using Autolayout Programmatically, for

我已经创建了 TKScroller 作为 UIView 的子类，我使用 Some Mode 和 Array 对其进行初始化.

I have Created TKScroller as subclass of UIView, I am init it using Some Mode and Array.

TKScroller.m

TKScroller.m

-(void)setData{

[self layoutIfNeeded];
CGRect mainFrame=self.frame;


[self layoutIfNeeded];
CGRect mainFrame=self.frame;
UIView *lastview;
NSMutableArray* manualConstraints = [NSMutableArray array];

for (int i=0; i<arrayData.count ; i++)
{
    CGRect frame;
    frame.origin.x = scrollView.frame.size.width * i;
    frame.origin.y = 0;
    frame.size = scrollView.frame.size;

    UIView *subview = [UIView new];

    subview.backgroundColor = [self getRandomColor];
    [scrollView addSubview:subview];

    if (i==0)
    {

        NSLayoutConstraint* b1_top = [NSLayoutConstraint constraintWithItem:subview attribute:NSLayoutAttributeTop relatedBy:NSLayoutRelationEqual toItem:scrollView attribute:NSLayoutAttributeTop multiplier:1 constant:5];
        [manualConstraints addObject:b1_top];

        NSLayoutConstraint* b1_left = [NSLayoutConstraint constraintWithItem:subview attribute:NSLayoutAttributeLeading relatedBy:NSLayoutRelationEqual toItem:scrollView attribute:NSLayoutAttributeLeading multiplier:1 constant:5];
        [manualConstraints addObject:b1_left];

        NSLayoutConstraint* b1_right = [NSLayoutConstraint constraintWithItem:subview attribute:NSLayoutAttributeTrailing relatedBy:NSLayoutRelationEqual toItem:scrollView attribute:NSLayoutAttributeTrailing multiplier:1 constant:-5];
        [manualConstraints addObject:b1_right];
        NSLayoutConstraint* b1_bottom = [NSLayoutConstraint constraintWithItem:subview attribute:NSLayoutAttributeBottom relatedBy:NSLayoutRelationEqual toItem:scrollView attribute:NSLayoutAttributeTop multiplier:1 constant:-10];
        [manualConstraints addObject:b1_bottom];

        [subview layoutIfNeeded];
        [scrollView addConstraints:manualConstraints];
        lastview=subview;
    }
    else{

        NSLayoutConstraint* b1_top = [NSLayoutConstraint constraintWithItem:subview attribute:NSLayoutAttributeTop relatedBy:NSLayoutRelationEqual toItem:scrollView attribute:NSLayoutAttributeTop multiplier:1 constant:5];
        [manualConstraints addObject:b1_top];

        NSLayoutConstraint* b1_left = [NSLayoutConstraint constraintWithItem:subview attribute:NSLayoutAttributeLeading relatedBy:NSLayoutRelationEqual toItem:lastview attribute:NSLayoutAttributeLeading multiplier:1 constant:5];
        [manualConstraints addObject:b1_left];

        NSLayoutConstraint* b1_right = [NSLayoutConstraint constraintWithItem:subview attribute:NSLayoutAttributeTrailing relatedBy:NSLayoutRelationEqual toItem:scrollView attribute:NSLayoutAttributeTrailing multiplier:1 constant:-5];
        [manualConstraints addObject:b1_right];
        NSLayoutConstraint* b1_bottom = [NSLayoutConstraint constraintWithItem:subview attribute:NSLayoutAttributeBottom relatedBy:NSLayoutRelationEqual toItem:scrollView attribute:NSLayoutAttributeTop multiplier:1 constant:-10];
        [manualConstraints addObject:b1_bottom];

        [subview layoutIfNeeded];
        [scrollView addConstraints:manualConstraints];
        lastview=subview;

    }
}

scrollView.contentSize = CGSizeMake(scrollView.frame.size.width * arrayData.count, mainFrame.size.height/2);

self.pageControl.currentPage = 0;
self.pageControl.numberOfPages = arrayData.count;

 pageControlBeingUsed = NO;
}

-(UIColor *)getRandomColor{
    int r = arc4random() % 255;
    int g = arc4random() % 255;
    int b = arc4random() % 255;
    return [UIColor colorWithRed:(r/255.0) green:(g/255.0) blue:(b/255.0) alpha:1.0];
}

现在我正在获取任何子视图，

Right now i am getting any subviews,

但是如果我改变方向它会给出不正确的结果，那么我怎样才能为滚动视图的子视图提供 NSLayoutConstraint 呢?

but if i change orientation it will give incorrect result, So how can i give NSLayoutConstraint for subviews of scrollview ?

编辑

添加 NSLayoutConstraint 后，子视图不显示.我只是缺少一些约束，请在动态设置约束时纠正我.

After adding NSLayoutConstraint subviews are not shown. I am just missing some constraint , please correct me in setting constraints dynamically.

我的源代码在这里，请帮帮我.谢谢你.抱歉语法不好.

My Source Code is here , Please Help Me. Thank you. And Sorry for bad grammar.

推荐答案

Here is a SO answer 解释了如何使用自动布局做到这一点，他已经完美地解释了，这里有垂直文本字段，但在你的情况下，你必须设置水平视图约束.

Here is a SO answer has explained how to do this with auto layout, he has explain perfectly , In here there is vertically textfields are there But in your case it is you have to set Horizontal views constraints.

替代方案

设置约束你可以只设置子视图的框架并在滚动视图中设置它，并且基于方向你可以改变滚动视图的子视图的框架.

Rather that setting constraints you can set just frame of the subview and set it in Scrollview, And based on orientation you can change frames of the scrolview's subviews.

你的 setData 方法比如，

Your setData Method like,

-(void)setData{

    [self layoutIfNeeded];
    CGRect mainFrame=scrollView.frame;
    CGRect frame;
    for (int i=0; i<arrayData.count ; i++)
    {
        CGRect frame;
        frame.origin.x = scrollView.frame.size.width * i;
        frame.origin.y = 0;
        frame.size = scrollView.frame.size;

        frame.origin=CGPointMake(0, 0);
        UIView *subview = [[UIView alloc]initWithFrame:frame];
        subview.backgroundColor = [self getRandomColor];
        [scrollView addSubview:subview];
    }
    scrollView.contentSize = CGSizeMake(scrollView.frame.size.width * arrayData.count, mainFrame.size.height/2);
}

现在你使用 NSNotificationCenter 可以在设备方向改变时得到通知，所以在它的这个选择器方法中调用你的 setData 方法，

Now you using NSNotificationCenter you can get notify when device orientation chaged, so in this selector method of it call your setData method,

[[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(setData)
                                                 name:UIDeviceOrientationDidChangeNotification
                                               object:nil];

现在在您的 setData 方法中，您需要删除所有子视图，因为当设备更改方向时，它将向您的滚动视图添加新视图，因此在设置其框架之前从 Scrollview 中删除所有子视图，

Now in you setData method you need remove all subviews because when device changes Orientation it will add new views to your scrollview, so remove all subview from Scrollview before setting its frame,

        [scrollView.subviews makeObjectsPerformSelector:@selector(removeFromSuperview)];

确保您正在从班级中移除观察者，例如，

Make sure you are removing observer from your class like,

- (void)dealloc
{
    [[NSNotificationCenter defaultCenter] removeObserver:self];
}

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