iOS 下拉菜单的简单实现以及使用

效果图

效果图.png

下拉列表选择类

1. .h文件

#import <UIKit/UIKit.h>

@interface ZPullMenu : UITableView

//头部视图
@property (nonatomic, strong) UIView *headView;

//头部视图数据
@property (nonatomic, copy) NSArray *headDataSource;

//头部视图选择行的数据
@property (nonatomic, copy) NSString *headText;

//选择的某一行返回的index
@property (nonatomic, strong) void (^selectBlock)(NSInteger);

@end

2. .m文件

#import "ZPullMenu.h"


@interface ZPullMenu()<UITableViewDelegate,UITableViewDataSource>
{
    UILabel *_label;//头部视图的Label
    UIImageView *_imageView;//头部视图选择按钮
    UITapGestureRecognizer *_tap;//选择按钮的手势
    BOOL _se;//判断是否点击了按钮
    NSString *_symbol;//箭头的指示
    CGRect _rect;// 存放当前视图frame的值
}
@end

@implementation ZPullMenu
- (instancetype)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame style:UITableViewStylePlain];
    if (self) {
        _rect = self.frame;
        // 初始化头部视图的Label的text为“结构树导航”
        self.headText = @"";
        // 初始化头部视图的选择按钮的图片名字
        _symbol = @"ZQ_zuojiankuohao";
        //创建手势
        _tap = [[UITapGestureRecognizer alloc]initWithTarget:self action:@selector(respondsToTap:)];
        // 设置代理
        self.dataSource = self;
        self.delegate = self;
        // 设置数据
        self.headDataSource = @[];
        // 初始化点击按钮bool值为NO
        _se = NO;
        // 设置表格不能上下拉动
        self.scrollEnabled = YES;
    }
    return self;
}
#pragma mark *** Events ***
/**
 *  手势的响应事件
 *
 *  @param gestuer 传递过来的手势
 */
- (void)respondsToTap:(UITapGestureRecognizer *)gestuer{
    if (!_se) {
        // 点击之后改变按钮的图片
        _symbol = @"ZQ_xiajiankuohao";
        // 将是否点击置为YES
        _se = YES;
        // 改变表格的大小
        self.frame = CGRectMake(self.frame.origin.x, self.frame.origin.y, self.bounds.size.width, 200);
        
    }else{
        _symbol = @"ZQ_zuojiankuohao";
        self.frame = CGRectMake(self.frame.origin.x, self.frame.origin.y, self.bounds.size.width, 40);
        _se = NO;
        
    }
    [self reloadData];
}


#pragma mark *** Protocol ***
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{
    static NSString *kcellId = @"zhaoqian";
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:kcellId];
    if (!cell) {
        cell = [[UITableViewCell alloc]initWithStyle:UITableViewCellStyleValue1 reuseIdentifier:kcellId];
    }
    cell.textLabel.text = self.headDataSource[indexPath.row];
    cell.backgroundColor = [UIColor colorWithRed:218.0/255.0 green:236.0/255.0 blue:247.0/255.0 alpha:1.0];
    return cell;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{
    if (_se) {
        return self.headDataSource.count;
    }else{
        return 0;
    }
}
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView{
    return 1;
}
- (CGFloat)tableView:(UITableView *)tableView heightForHeaderInSection:(NSInteger)section{
    return 40;
}
- (UIView *)tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section{
    self.headView = [[UIView alloc]initWithFrame:CGRectMake(0, 0, self.bounds.size.width, 40)];
    _label = [[UILabel alloc]initWithFrame:CGRectMake(0, 0, self.bounds.size.width - 40, 40)];
    _label.font = [UIFont systemFontOfSize:20];
    _label.text = [NSString stringWithFormat:@"%@",self.headText];
    _label.textColor = [UIColor whiteColor];
    [_label setTextAlignment:NSTextAlignmentCenter];
    _imageView = [[UIImageView alloc]initWithFrame:CGRectMake(CGRectGetMaxX(_label.frame), 0, 40, 40)];
    _imageView.userInteractionEnabled = YES;
    [_imageView addGestureRecognizer:_tap];
    _imageView.image = [UIImage imageNamed:_symbol];
    [self.headView addSubview:_label];
    [self.headView addSubview:_imageView];
    self.headView.backgroundColor = [UIColor colorWithRed:31.0/255.0 green:105.0/255.0 blue:114.0/255.0 alpha:1.0];
    return self.headView;
}
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath{
    // 点击某个单元格之后（和点击按钮的事件对比可知）
    self.headText = self.headDataSource[indexPath.row];
    _se = NO;
    self.frame =_rect;
    _symbol = @"ZQ_zuojiankuohao";
    if (self.selectBlock) {
        self.selectBlock(indexPath.row);
    }
    [self reloadData];
}

@end

3. 使用
   在ViewController中使用
   demo的代码示例：

#import "ViewController.h"
#import "ZPullMenu.h"

@interface ViewController ()

@property (nonatomic, strong)ZPullMenu *pullMenu;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    [self.view addSubview:self.pullMenu];
    // Do any additional setup after loading the view, typically from a nib.
}


- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}
- (ZPullMenu *)pullMenu{
    if (!_pullMenu) {
        _pullMenu = [[ZPullMenu alloc]initWithFrame:CGRectMake(100, 100, 200, 40)];
        
        _pullMenu.headDataSource = @[@"zq0",@"zq1",@"zq2",@"zq3"];
    }
    return _pullMenu;
}
@end

说明：这是很早之前写的一个，初始化的时候需要设置frame的高度为40，展开之后默认为200的高度。当然，有需要的话自己可以在代码中修改高度。

资源：里面用到的箭头的图片

ZQ_xiajiankuohao.png
ZQ_zuojiankuohao.png