如何以编程方式使用自动布局添加自定义视图

Question

我的故事板有一个包含 UIScrollView 的视图控制器。我想在 viewController 中以编程方式向滚动视图添加一些自定义视图（每个视图将包含一个图像和标签）。我在情节提要中为 UIScrollView 设置了约束，但努力添加带有约束的自定义视图。我怎样才能做到这一点，以便它可以在所有设备（iPhone/iPad）上显示为相同？我尝试了下面的方法，但它似乎不起作用。

在我的 ViewController.m 中 -

#import "MainViewController.h"

#define DEFAULT_ROW_HEIGHT 50

@interface MainViewController ()

@property float topMarginFromUpperView;

@end

@implementation MainViewController

-(void) addCustomRowToView {
    self.topMarginFromUpperView += DEFAULT_ROW_HEIGHT + 10.0f;
    UIView *customRow = [[UIView alloc] initWithFrame:self.scrollView.bounds];
    customRow.backgroundColor = [UIColor redColor];
    [self.scrollView addSubview:customRow];

    customRow.translatesAutoresizingMaskIntoConstraints = NO;

    [self.scrollView addConstraint:[NSLayoutConstraint constraintWithItem:customRow attribute:NSLayoutAttributeTop relatedBy:NSLayoutRelationEqual toItem:self.scrollView attribute:NSLayoutAttributeTop multiplier:1.0f constant:self.topMarginFromUpperView]];
    [self.scrollView addConstraint:[NSLayoutConstraint constraintWithItem:customRow attribute:NSLayoutAttributeLeading relatedBy:NSLayoutRelationEqual toItem:self.scrollView attribute:NSLayoutAttributeLeading multiplier:1.0f constant:10.0f]];
    [self.scrollView addConstraint:[NSLayoutConstraint constraintWithItem:customRow attribute:NSLayoutAttributeTrailing relatedBy:NSLayoutRelationEqual toItem:self.scrollView attribute:NSLayoutAttributeTrailing multiplier:1.0f constant:-10.0f]];
    [self.scrollView addConstraint:[NSLayoutConstraint constraintWithItem:customRow attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:self.scrollView attribute:NSLayoutAttributeHeight multiplier:0.1f constant:0.0f]];
}

- (void)viewDidLoad {
    [super viewDidLoad];

    self.topMarginFromUpperView = 0.0f;
    for (NSInteger i =0; i< 10; i++) {
        [self addCustomRowToView];
    }
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

@end

已编辑：

仍在为约束设置而苦苦挣扎。由于无效约束，应用程序崩溃。尝试如下-

-(void) setConstraints:(UIView *)customRow {

    [self.scrollView addConstraint:[NSLayoutConstraint constraintWithItem:customRow attribute:NSLayoutAttributeTop relatedBy:NSLayoutRelationEqual toItem:self.scrollView attribute:NSLayoutAttributeTop multiplier:1.0f constant:self.topMarginFromSuperView]];
    [self.scrollView addConstraint:[NSLayoutConstraint constraintWithItem:customRow attribute:NSLayoutAttributeLeading relatedBy:NSLayoutRelationEqual toItem:self.scrollView attribute:NSLayoutAttributeLeading multiplier:1.0f constant:10.0f]];
    [self.scrollView addConstraint:[NSLayoutConstraint constraintWithItem:customRow attribute:NSLayoutAttributeTrailing relatedBy:NSLayoutRelationEqual toItem:self.scrollView attribute:NSLayoutAttributeTrailing multiplier:1.0f constant:-10.0f]];
    [self.scrollView addConstraint:[NSLayoutConstraint constraintWithItem:customRow attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:self.scrollView attribute:NSLayoutAttributeHeight multiplier:0.1f constant:0.0f]];
}

-(void) addCustomRowToView {
    UIView *customRow = [[UIView alloc]initWithFrame:CGRectMake(DEFAULT_PADDING, self.topMarginFromSuperView, self.view.bounds.size.width - 2*DEFAULT_PADDING, DEFAULT_ROW_HEIGHT)];
    customRow.backgroundColor = [UIColor redColor];
    customRow.translatesAutoresizingMaskIntoConstraints = NO;

    [self setConstraints:customRow];

    [self.scrollView addSubview:customRow];
    self.scrollView.contentSize = CGSizeMake(self.view.bounds.size.width, self.topMarginFromSuperView + DEFAULT_ROW_HEIGHT);
    self.topMarginFromSuperView += DEFAULT_ROW_HEIGHT + DEFAULT_PADDING;
}

- (void)viewDidLoad {
    [super viewDidLoad];

    self.topMarginFromSuperView = 0.0f;
    //for (NSInteger i =0; i< 10; i++) {
        [self addCustomRowToView];
   // }
   } 

@end

Answer 1

这里是您的问题的解决方案：

 - (void)addCustomView
{
    UIView *lastView;
    for (int i = 0; i<10; i++)
    {
        UIView *view = [[UIView alloc] init];
        view.backgroundColor = i%2 ? [UIColor redColor] : [UIColor greenColor];
        view.translatesAutoresizingMaskIntoConstraints = NO;
        [self.scrollView addSubview:view];
        [self.scrollView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-10-[view]-10-|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(view)]];
        [self.scrollView addConstraint:[NSLayoutConstraint constraintWithItem:view attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationEqual toItem:self.scrollView attribute:NSLayoutAttributeWidth multiplier:1 constant:-20.0]];

        if (i == 0)
        {
            [self.scrollView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|[view(40)]" options:0 metrics:nil views:NSDictionaryOfVariableBindings(view)]];

        }
        else
        {
            [self.scrollView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:[lastView(40)]-10-[view(40)]" options:0 metrics:nil views:NSDictionaryOfVariableBindings(lastView,view)]];
        }
        lastView = view;
    }
    [self.scrollView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:[lastView(40)]|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(lastView)]];
}