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ios – 如何使用AutoLayout在UIScrollView中编程子视图？

2020年01月23日 作者：佚名
我正在使用Autolayout Progrmatically创建UiScrollview和UIPagectontrol的应用程序

我创建了TKScroller作为UIView的子类,我使用一些模式和数组来初始化它.

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];
}

现在我得到任何子视图,

但是如果我改变方向会给出不正确的结果,那么我如何给NSLayoutConstraint的scrollview子视图？

编辑

添加NSLayoutConstraint子视图后不会显示.我只是错过了一些约束,请在动态设置约束时纠正我.

我的Source Code is here,请帮我
谢谢.对不起,糟糕的语法.

解决方法

Here is a SO answer已经解释了如何做到这一点与汽车布局,他已经解释完美,在这里有垂直的textfields在那里但在你的情况下,你必须设置水平视图约束.

替代

而是设置约束,您可以设置子视图的框架,并将其设置在ScrollView中,并且根据方向,您可以更改scrolview的子视图的框架.

你的setData方法就像,

-(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可以在设备方向被通知时得到通知,所以在这种选择器方法中,它调用你的setData方法,

[[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Orientation时,它将向scrollview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,

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

确保你从你的类中删除观察者,

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

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