给UIScrollView+代码约束

2026-01-02 07:38:26

1、用xcode创建一个新工程，然后打开ViewController.m文件

给UIScrollView+代码约束

2、我们在ViewController的viewDidLoad方法里创建一个UIScrollView并且加上约束

代码如下:

//创建scrollView

UIScrollView * scrollView=[[UIScrollView alloc] init];

scrollView.translatesAutoresizingMaskIntoConstraints=NO;

scrollView.backgroundColor=[UIColor lightGrayColor];

[self.view addSubview:scrollView];

//给它加上约束使它距屏幕的上左下右都是20像素

[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-20-[scrollView]-20-|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(scrollView)]];

[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-20-[scrollView]-20-|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(scrollView)]];

效果如图

给UIScrollView+代码约束

3、我要再创建两个view 这两个view的大小和scrollview的大小一样大，使scrollview能横向滚动

代码如下:

//添加约束 (非常重要)

//1.水平方向排开宽度相等上下边缘对齐(等高)

[scrollView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-0-[redView]-0-[blueView(==redView)]-0-|" options:NSLayoutFormatAlignAllTop | NSLayoutFormatAlignAllBottom metrics:nil views:NSDictionaryOfVariableBindings(redView,blueView)]];

//2.垂直方向一直撑到父视图的

[scrollView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-0-[redView]-0-|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(redView)]];

//到了这里还没完如果是普通的view 那就搞定了但是scrollview不一样还得添加下面两个约束

//3.redview的宽高和scrollview的宽高相等的约束

[scrollView addConstraint:[NSLayoutConstraint constraintWithItem:redView attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationEqual toItem:scrollView attribute:NSLayoutAttributeWidth multiplier:1.0 constant:0]];

[scrollView addConstraint:[NSLayoutConstraint constraintWithItem:redView attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:scrollView attribute:NSLayoutAttributeHeight multiplier:1.0 constant:0]];

给UIScrollView+代码约束

4、整个viewdidload全部代码如下：

- (void)viewDidLoad

{

[super viewDidLoad];

//创建scrollView

UIScrollView * scrollView=[[UIScrollView alloc] init];

scrollView.translatesAutoresizingMaskIntoConstraints=NO;

scrollView.backgroundColor=[UIColor lightGrayColor];

[self.view addSubview:scrollView];

//给它加上约束使它距屏幕的上左下右都是20像素

[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-20-[scrollView]-20-|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(scrollView)]];

[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-20-[scrollView]-20-|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(scrollView)]];

//创建redView

UIView * redView=[[UIView alloc] init];

redView.backgroundColor=[UIColor redColor];

redView.translatesAutoresizingMaskIntoConstraints=NO;

[scrollView addSubview:redView];

//创建blueView

UIView * blueView=[[UIView alloc] init];

blueView.backgroundColor=[UIColor blueColor];

blueView.translatesAutoresizingMaskIntoConstraints=NO;

[scrollView addSubview:blueView];

//添加约束 (非常重要)

//1.水平方向排开宽度相等上下边缘对齐(等高)

//2.垂直方向一直撑到父视图的

[scrollView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-0-[redView]-0-|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(redView)]];

//3.redview的宽高和scrollview的宽高相等的约束

}

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