UIButton的自动排列

最近在工作中用到了UIButton的排布，需求是根据button的不同宽度（高度相同）实现自动排布。这是第四次用到了，前面分别写了3个项目，用到了三次，感觉还是比较常用的小功能；第一次自己写了个算法，第二次和三次写成固定宽高的按钮规则排布，这次由于要适应不同宽度的需要，在原有基础上做了修改，可以适应不同的按钮宽度，布局自动计算。

---

目录

实现效果

基本思路

核心问题是根据button的数量，和每一个button的宽度（宽度由文字多少决定）计算button的排布，button高度和内间距可以设为固定常数。
1. 将创建好的按钮放在数组中；
2. 解决分类和计算逻辑：先确定第一个button的位置，然后计算第二个button的位置，第二个button的位置可能在当前行，也可能在下一行。需要两个if else嵌套，在循环遍历button的过程中，动态确定每一个button的位置。

核心代码

1.创建继承于UIView的子类：ButtonLayoutView，在ButtonLayoutView.m中实现计算：

#import "ButtonsLayoutView.h"

CGFloat const buttonH = 30;
CGFloat const buttonInset = 20;

@interface ButtonsLayoutView()
/** button array */
@property (strong, nonatomic) NSMutableArray *buttonArray;
@end

@implementation ButtonsLayoutView

-(NSMutableArray *)buttonArray {
    if (!_buttonArray) {
        _buttonArray = [NSMutableArray array];
    }
    return _buttonArray;
}

- (instancetype)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        [self createButtons:@[@"30 g",@"20 g",@"40 g",@"50 g",@"样例样例",@"样例样例样例",@"样例",@"30 g",@"20 g",@"40 g",@"50 g",@"样例样例",@"样例样例样例",@"样例"]];
    }
    return self;
}

- (void)createButtons:(NSArray *)titles{
    for (int i = 0; i < titles.count; i++) {
        UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
        button.backgroundColor = [UIColor purpleColor];
        [button setTitle:titles[i] forState:UIControlStateNormal];
        [self addSubview:button];

        // calucate frame
        [button sizeToFit];
        CGRect rect = button.frame;
        rect.size.width += 2 * buttonInset;
        rect.size.height = buttonH;
        button.frame = rect;
        // add array
        [self.buttonArray addObject:button];
    }
}

- (void)layoutSubviews {
    [super layoutSubviews];
    for (int i = 0; i < self.buttonArray.count; i ++) {
        // 1.take out button
        UIButton *button = self.buttonArray[i];
        CGRect rect = button.frame;
        CGRect superRect = self.frame;
        // 2.calucate layout
        if (i == 0) { // the first button
            rect.origin.x = buttonInset;
            rect.origin.y = buttonInset;
        } else { // the behind button
            UIButton *lastButton = self.buttonArray[i - 1];
            CGRect lastRect = lastButton.frame;
            CGFloat leftButtonW = CGRectGetMaxX(lastButton.frame) + buttonInset;
            // over legnth
            CGFloat rightW = superRect.size.width - leftButtonW - buttonInset;
            if (rightW < rect.size.width) { // next line
                rect.origin.x = buttonInset;
                rect.origin.y = CGRectGetMaxY(lastButton.frame) + buttonInset;

            } else {// current line
                rect.origin.x = leftButtonW;
                rect.origin.y = lastRect.origin.y;
            }
        }

        button.frame = rect;
    }
    // superView Height
    UIButton *button = [self.buttonArray lastObject];
    CGRect rect = self.frame;
    rect.size.height = CGRectGetMaxY(button.frame) + buttonInset;
    self.frame = rect;
}

@end

2.测试：在ViewController.m中导入ButtonLayoutView的头文件，开始使用，需要给出ButtonsLayoutView的宽度，和起点坐标，高度会自动被计算：

- (void)viewDidLoad {
    [super viewDidLoad];
    ButtonsLayoutView *layoutView = [[ButtonsLayoutView alloc]init];
    layoutView.backgroundColor = [UIColor brownColor];
    CGRect rect = layoutView.frame;
    rect.size.width = 300;
    rect.origin.x = 50;
    rect.origin.y = 50;
    layoutView.frame = rect;
    layoutView.clipsToBounds = YES;
    [self.view addSubview:layoutView];
}

附录：固定列数的button布局

利用固定列计算button布局，带单选功能。

效果图

核心代码

1.定义

#import "ZFLReportAbuse.h"

@interface ZFLReportAbuse()
/** 被选中的button */
@property (strong, nonatomic) UIButton *selectedButton;
@end

@implementation ZFLReportAbuse

- (instancetype)initWithFrame:(CGRect)frame {
    if (self = [super initWithFrame:frame]) {
        self.backgroundColor = ZFLRGBColor(30, 30, 30);
        NSArray *titleArray = @[@"网络盗图",@"垃圾广告",@"不实信息",@"敏感信息",@"其他",@"人身攻击"];
        // 最大列数
        int maxCols = 2;
        // 根据最大列算最大行数
        int maxRows;
        if (titleArray.count <= 3) {
            maxRows = 1;
        } else {
            // 整除,除尽
            BOOL isDivisible = (titleArray.count % maxCols) == 0;
            if (isDivisible) {
                maxRows = (int)titleArray.count / maxCols;
            } else {
                maxRows = (int)titleArray.count / maxCols + 1;
            }
        }

        CGFloat insetMargin = 15;
        CGFloat buttonHeight = 30;
        for (int i = 0; i < titleArray.count; i++) {
            UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
            [button setTitle:titleArray[i] forState:UIControlStateNormal];
            [button setTitleColor:[UIColor whiteColor] forState:UIControlStateNormal];
            [button setImage:[UIImage imageNamed:@"normal_icon"] forState:UIControlStateNormal];
            [button setImage:[UIImage imageNamed:@"selected_icon"] forState:UIControlStateSelected];
            button.contentHorizontalAlignment = UIControlContentHorizontalAlignmentLeft;
            button.width = 100;
            button.height = buttonHeight;
            button.top = insetMargin  + (i / maxCols) * button.height + (i / maxCols) * insetMargin;
            button.left = insetMargin  + (i % maxCols) * button.width + (i % maxCols) * insetMargin;
            [button addTarget:self action:@selector(buttonClick:) forControlEvents:UIControlEventTouchUpInside];
            [self addSubview:button];

            // 默认选中第一个
            if (i == 0) {
                button.selected = YES;
                self.selectedButton = button;
            }

            self.height = (buttonHeight + insetMargin) * maxRows + insetMargin;
            self.width = SCREEN_WIDTH;
        }

    }
    return self;
}

- (void)buttonClick:(UIButton *)button {
    self.selectedButton.selected = NO;
    self.selectedButton = button;
    self.selectedButton.selected = YES;
}

@end

2.使用

ZFLReportAbuse *reportView = [[ZFLReportAbuse alloc]init];
reportView.top = 44;
reportView.left = 0;
[self.view addSubview:reportView];