效果如上图所示，很多APP里面都有这样的效果。

实现的大致过程：用户点击的时候，初始化一个UIView,UIView的背景色为clearcolor,然后在UIView里面添加一个tableview。

代码：

//
//  LrdCustomMenu.m
//  加号菜单
//
//  Created by 键盘上的舞者 on 15/11/26.
//  Copyright © 2015年 键盘上的舞者. All rights reserved.
//

#import "LrdCustomMenu.h"

#define TopToView 10.0f
#define LeftToView 10.0f
#define CellLineEdgeInsets UIEdgeInsetsMake(0, 10, 0, 10)
#define kScreenWidth        [UIScreen mainScreen].bounds.size.width
#define kScreenHeight        [UIScreen mainScreen].bounds.size.height

@interface LrdCustomMenu()
@property(nonatomic,assign) CGPoint origin;
@property(nonatomic,assign) CGFloat height;
@end

@implementation LrdCustomMenu

-(instancetype)initWithDataArr:(NSArray *)dataArray origin:(CGPoint)origin width:(CGFloat)width height:(CGFloat)height
{
    self=[super initWithFrame:CGRectMake(0, 0, kScreenWidth, kScreenHeight)];
    if (self) {
        if (height<=0) {
            self.height=44;
        }
        self.origin=origin;
        self.height=height;
        self.arrData=[dataArray copy];
        self.backgroundColor=[UIColor clearColor];
        self.tableView=[[UITableView alloc] initWithFrame:CGRectMake(origin.x+LeftToView, origin.y+TopToView, width, height*dataArray.count) style:UITableViewStylePlain];
        _tableView.delegate=self;
        _tableView.dataSource=self;
        [self addSubview:_tableView];
        _tableView.backgroundColor = [UIColor colorWithWhite:0.2 alpha:1];
        _tableView.layer.cornerRadius = 2;
        _tableView.bounces = NO;
        _tableView.separatorColor = [UIColor colorWithWhite:0.3 alpha:1];
        [_tableView registerClass:[UITableViewCell class] forCellReuseIdentifier:@"LrdCustomMenu"];
        if ([self.tableView respondsToSelector:@selector(setSeparatorInset:)]) {
            [self.tableView setSeparatorInset:CellLineEdgeInsets];
        }
        
        if ([self.tableView respondsToSelector:@selector(setLayoutMargins:)]) {
            [self.tableView setLayoutMargins:CellLineEdgeInsets];
        }
    }
    return self;
}

-(NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    return self.arrData.count;
}

-(CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
    return self.height;
}

-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"LrdCustomMenu"];
    cell.backgroundColor = [UIColor clearColor];
    cell.textLabel.textColor = [UIColor whiteColor];
    cell.textLabel.font = [UIFont systemFontOfSize:15];
    cell.textLabel.text = self.arrData[indexPath.row];
    if (self.arrImgName.count > indexPath.row) {
        cell.imageView.image = [UIImage imageNamed:self.arrImgName[indexPath.row]];
    }
    cell.selectedBackgroundView = [[UIView alloc] initWithFrame:cell.frame];
    cell.selectedBackgroundView.backgroundColor = [UIColor blackColor];
    return cell;
}

-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    if ([self.delegate respondsToSelector:@selector(LrdCustomMenu:didSelectedAtIndexPath:)]) {
        [self.delegate LrdCustomMenu:tableView didSelectedAtIndexPath:indexPath];
    }
    [tableView deselectRowAtIndexPath:indexPath animated:YES];
    [self dissmissWithCompletion:nil];
}


-(void)dissmissWithCompletion:(void (^)(LrdCustomMenu *))completion
{
    __weak __typeof(self) weakSelf = self;
    [UIView animateWithDuration:0.2 animations:^{
        weakSelf.alpha = 0;
        weakSelf.tableView.frame = CGRectMake(weakSelf.origin.x + LeftToView, weakSelf.origin.y + TopToView, 0, 0);
    } completion:^(BOOL finished) {
        [weakSelf removeFromSuperview];
        if (completion) {
            completion(weakSelf);
        }
        if (weakSelf.dismiss) {
            weakSelf.dismiss();
        }
    }];
}

-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
{
    UITouch *touch = [touches anyObject];
    if (![touch.view isEqual:self.tableView]) {
        [self dissmissWithCompletion:nil];
    }
}

- (void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath

{
    
    if ([cell respondsToSelector:@selector(setSeparatorInset:)]) {
        
        [cell setSeparatorInset:CellLineEdgeInsets];
        
    }
    
    if ([cell respondsToSelector:@selector(setLayoutMargins:)]) {
        
        [cell setLayoutMargins:CellLineEdgeInsets];
        
    }
    
}
- (void)drawRect:(CGRect)rect

{
    
    
    //    [colors[serie] setFill];
    
    //拿到当前视图准备好的画板
    
    CGContextRef
    context = UIGraphicsGetCurrentContext();
    
    //利用path进行绘制三角形
    
    CGContextBeginPath(context);//标记
    
    CGContextMoveToPoint(context,
                         LeftToView * 2.5, TopToView * 0.5);//设置起点
    
    CGContextAddLineToPoint(context,
                            LeftToView * 2, TopToView);
    
    CGContextAddLineToPoint(context,
                            LeftToView * 3, TopToView);
    
    CGContextClosePath(context);//路径结束标志，不写默认封闭
    
    [self.tableView.backgroundColor setFill]; //设置填充色
    
    //    [self.tableView.backgroundColor setStroke]; //设置边框颜色
    
    CGContextDrawPath(context,
                      kCGPathFillStroke);//绘制路径path
}

@end

//
//  LrdCustomMenu.h
//  加号菜单
//
//  Created by 键盘上的舞者 on 15/11/26.
//  Copyright © 2015年 键盘上的舞者. All rights reserved.
//

#import <UIKit/UIKit.h>

@protocol LrdCustomMenuDelegate <NSObject>

@optional
-(void)LrdCustomMenu:(UITableView *)tableview didSelectedAtIndexPath:(NSIndexPath *)indexPath;

@end


typedef void(^Dismiss)(void);
@interface LrdCustomMenu : UIView<UITableViewDataSource,UITableViewDelegate>

@property (nonatomic, strong) UITableView *tableView;
@property (nonatomic, assign) id<LrdCustomMenuDelegate> delegate;
@property (nonatomic, strong) NSArray *arrData;
@property (nonatomic, strong) NSArray *arrImgName;
@property (nonatomic, copy) Dismiss dismiss;

//初始化类方法
-(instancetype)initWithDataArr:(NSArray *)dataArray origin:(CGPoint)origin width:(CGFloat)width height:(CGFloat)height;

//销毁的时候的Block
-(void)dissmissWithCompletion:(void (^)(LrdCustomMenu *obj))completion;

@end

//
//  ViewController.m
//  加号菜单
//
//  Created by 键盘上的舞者 on 15/11/26.
//  Copyright © 2015年 键盘上的舞者. All rights reserved.
//

#import "ViewController.h"
#import "LrdCustomMenu.h"

@interface ViewController ()<LrdCustomMenuDelegate>
@property(nonatomic,strong) LrdCustomMenu *menu;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    self.navigationController.navigationBar.translucent=NO;
    //添加左侧的item
    UIBarButtonItem *item=[[UIBarButtonItem alloc] initWithImage:[UIImage imageNamed:@"schoolListItem"] style:UIBarButtonItemStylePlain target:self action:@selector(showMenu:)];
    self.navigationItem.leftBarButtonItem=item;
    
}
-(void)showMenu:(UIBarButtonItem *)buttonItem
{
    __weak __typeof(self) weakSelf = self;
    if (!self.menu) {
        self.menu = [[LrdCustomMenu alloc] initWithDataArr:@[@"附近学校", @"联赛流程", @"其他联赛", @"校内群聊", @"邀请好友"] origin:CGPointMake(0, 0) width:125 height:44];
        _menu.delegate = self;
        _menu.dismiss = ^() {
            weakSelf.menu = nil;
        };
        _menu.arrImgName = @[@"item_school", @"item_battle", @"item_list", @"item_chat", @"item_share"];
        [self.view addSubview:_menu];
    } else {
        [_menu dissmissWithCompletion:^(LrdCustomMenu *object) {
            weakSelf.menu = nil;
        }];
    }
}

-(void)LrdCustomMenu:(UITableView *)tableview didSelectedAtIndexPath:(NSIndexPath *)indexPath
{
    NSLog(@"select: %ld", indexPath.row);
}

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

@end