将子视图保留为 UIStackView 中的原始尺寸

Question

目前我正在尝试在 3 个水平组中制作 3 个具有相等间距的按钮

UIStackView * menuButtons = [[UIStackView alloc] initWithFrame:CGRectMake(0, 0, 60, 16)];
  menuButtons.axis = UILayoutConstraintAxisHorizontal;
  menuButtons.alignment = UIStackViewAlignmentBottom;
  menuButtons.spacing = 6;
  menuButtons.distribution = UIStackViewDistributionEqualSpacing;

UIButton* btnOne = [[UIButton alloc] initWithFrame:CGRectMake(0, 0, 16, 16)];
UIButton* btnTwo = [[UIButton alloc] initWithFrame:CGRectMake(0, 0, 16, 16)];
UIButton* btnThree = [[UIButton alloc] initWithFrame:CGRectMake(0, 0, 16, 16)];

  [menuButtons addArrangedSubview:btnOne];
  [menuButtons addArrangedSubview:btnTwo];
  [menuButtons addArrangedSubview:btnThree];

我注意到，当我以编程方式将按钮视图添加到我的堆栈视图后检查它们的框架时，它们都显示出与最初设置不同的大小，而我希望它们仍然是 16

即：btnOne CGSize(17, 16), btnTwo CGSize(23.5, 23,5), btnThree CGSize(21.3, 21.3)

我不明白为什么会发生这种情况，我已经尝试了所有发行版，但是当我没有在其他任何地方设置这些视图的框架时，我无法弄清楚这一点

Answer 1

这是一个示例 - 基于您的代码 - 使用自动布局约束。

请注意，您不需要为 UIStackView 指定宽度和高度约束，因为它会根据需要扩展以适应排列的子视图。

如果您确实设置了宽度限制，您最终会得到（可能）意想不到的结果，因为您也指定了6 的固定宽度间距。

所以，你会想要：

1. 宽度约束 + UIStackViewDistributionEqualSpacing，或者
2. 没有宽度限制 + 默认分布 + .spacing = 6

希望这会有所帮助...

//
//  StackTestViewController.m
//
//  Created by Don Mag on 6/24/17.
//

#import "StackTestViewController.h"

@interface StackTestViewController ()

@end

@implementation StackTestViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    [self setupMenuButtons];
}

- (void)setupMenuButtons {

    // instantiate a UIStackView
    UIStackView *menuButtons = [[UIStackView alloc] init];

    // horizontal
    menuButtons.axis = UILayoutConstraintAxisHorizontal;

    // spacing between arranged views
    menuButtons.spacing = 6;

    // instantiate 3 buttons
    UIButton* btnOne = [UIButton new];
    UIButton* btnTwo = [UIButton new];
    UIButton* btnThree = [UIButton new];

    // give 'em background colors so we can see them
    btnOne.backgroundColor = [UIColor redColor];
    btnTwo.backgroundColor = [UIColor greenColor];
    btnThree.backgroundColor = [UIColor blueColor];

    // for each button,
    //  tell it not to use Autoresizing Mask
    //  set width and height constraints each to 16
    for (UIButton *b in @[btnOne, btnTwo, btnThree]) {
        [b setTranslatesAutoresizingMaskIntoConstraints:NO];
        [b.widthAnchor constraintEqualToConstant:16.0].active = YES;
        [b.heightAnchor constraintEqualToConstant:16.0].active = YES;
    }

    // add them to the Stack View
    [menuButtons addArrangedSubview:btnOne];
    [menuButtons addArrangedSubview:btnTwo];
    [menuButtons addArrangedSubview:btnThree];

    // add the Stack View to self view
    [self.view addSubview:menuButtons];

    // tell Stack View not to use Autoresizing Mask
    [menuButtons setTranslatesAutoresizingMaskIntoConstraints:NO];

    // set X and Y position for the Stack View (just using 80,80 for this example)
    [menuButtons.leadingAnchor constraintEqualToAnchor:self.view.leadingAnchor constant:80.0].active = YES;
    [menuButtons.topAnchor constraintEqualToAnchor:self.view.topAnchor constant:80.0].active = YES;

}

#end