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ViewController.m

#import "ViewController.h"

@interface ViewController ()
//存放label的数组
@property(nonatomic,strong)NSMutableArray *labelArr;
@end

@implementation ViewController
//控制y坐标的变量
int newY = 80;
- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor lightGrayColor];
    //初始化添加按钮
    UIButton *addBtn = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    //设置背景颜色
    addBtn.backgroundColor = [UIColor orangeColor];
    addBtn.frame = CGRectMake(50, 20, 100, 30);
    [addBtn setTitle:@"添加" forState:UIControlStateNormal];
   
    [addBtn addTarget:self action:@selector(addLabel) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:addBtn];
   
   
    UIButton *deleBtn = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    //设置背景颜色
    deleBtn.backgroundColor = [UIColor orangeColor];
    deleBtn.frame = CGRectMake(200, 20, 100, 30);
    [deleBtn setTitle:@"删除" forState:UIControlStateNormal];
    [deleBtn addTarget:self action:@selector(deleLabel) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:deleBtn];
    //给数组开辟空间
    self.labelArr = [NSMutableArray array];
}
-(void)addLabel{
   
    //判断如果lable小于10个 添加label
    if (self.labelArr.count < 10) {
        UILabel *label = [[UILabel alloc]initWithFrame:CGRectMake(100, newY, 200, 40)];
        label.text = @"ok";
        label.textAlignment = NSTextAlignmentCenter;
       //arc4random获取随机数
        //颜色
        label.backgroundColor = [UIColor colorWithRed:arc4random()%10*0.1 green:arc4random()%10*0.1 blue:arc4random()%10*0.1 alpha:1];
        [self.labelArr addObject:label];
        [self.view addSubview:label];
        newY += 60;
    }else{

    [[[UIAlertView alloc]initWithTitle:@"提示" message:@"hello太多了！" delegate:self cancelButtonTitle:@"确定" otherButtonTitles: nil] show];
       
    }
}
-(void)deleLabel{
    if (self.labelArr.count >0) {
        //将label从视图中移除
        [[self.labelArr lastObject] removeFromSuperview];
        //从数组中删除数据
        [self.labelArr removeLastObject];
        newY -=60;
    }else{
        [[[UIAlertView alloc]initWithTitle:@"提示" message:@"没有hello了！" delegate:self cancelButtonTitle:@"确定" otherButtonTitles: nil] show];
   
    }

}

@end