不可变数组的一些方法与理解

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
  
    /*______________________________不可变数组______________________________*/
   //创建
 NSString *s1 [email protected]"wangwei";
 NSString *s2 [email protected]"wangwang";
 NSString *s3 [email protected]"weiwei";
 NSArray *array1 = [[NSArray alloc] initWithObjects:s1,s2,s3, nil];
 NSLog(@"%@",array1.description);
    //类方法创建
 NSArray *array2=  [NSArray arrayWithObjects:s1,s2,s3,nil];
 NSArray *array3 =  [NSArray arrayWithObject:s1];//只能存一个.
    
 NSArray *array4=[NSArray arrayWithArray:array1];//从array1里面的元素全部存储到一个新的数组类
    
 NSLog(@"%@",array4);//打印array4.大致可以理解为备份一份数组里元素到一个新的数组类

   /*_____________________________通过下标取元素_________________________*/
 NSString *str1 =[array4 objectAtIndex:0];
 NSLog(@"%@",str1);
   /*_____________________________获取元素个____________________________________*/
    
     NSUInteger count1 =[array4 count];
     NSUInteger count2 = array4.count;//等价于[array4 count];
     NSLog(@"count2 = %ld",count2);
    /*_____________________________判断数组中是否包含某个对象__________________*/

    BOOL isContains =[array4 containsObject:@"wangwei"];
    NSLog(@"isContains:%d",isContains);
     /*___________________________查找某一个对象在数组中的下标位置_______________*/
    NSUInteger index =[array4 indexOfObject:@"wangwei"];   //表示@"wangwei"是数组里的第几个元   
                                                                                         //素,从0开始的,将下标给于 index
    NSLog(@"index =%ld",index);
    NSUInteger index1 =[array4 indexOfObject:@"wangweitaishuaile"];
    if(index1 ==NSNotFound){         //NSNotfound  表示没有这个元素          
                                                   // 枚举enum {NSNotFound =NSIntegerMax}"枚举括号里没看懂
    NSLog(@"没有这个元素");        
    }
    else {
        NSLog(@"index1=%ld",index1);
    }
   /*______________________连接数组中的字符串________________________________*/
    NSString *joinstring =[array4 componentsJoinedByString:@"________"];//返回一个连接之后的字符串
    NSLog(@"joinstring =%@",joinstring);   //必须数字里都是字符串才可以使用这个方法
    /*______________________访问最后一个字符串_______________________________*/
    NSString *lastobj1 =[array4 lastObject];//可以使用点语法  两个条件,方法名要一样,有返回值,其实就等于get方法,就可以用点语法
    NSString *lastobj2 =array4.lastObject;
    NSLog(@"lastobj:%@,%@",lastobj1,lastobj2);
    /*_______________________在原来数组后面追加一个元素________________________*/
    NSArray *array5 =[array4 arrayByAddingObject:@"wangwangwei"];
    //由于不可变,所以追加的是新生成的数组,原来数组中的元素无法更改
    NSLog(@"%@",array5);
   //NSArray *array6 =[NSArray arrayWithObjects: ]不可以存放基本数据类型放入数组,数组是存的是指针
    //如果传入的数组的下标超过数组最大元素,会错误的.数组越界index4  beyond bounds[0..3];
    //可以加入判断    if (idx<array.count) ;
    return ;
}


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

@end

 下面是自己创的视图,以及理解,没有用到太多东西,按钮还是拖拽的

#import "ViewController.h"

@interface ViewController ()
{
    UIView *greenView;
}
@property (weak, nonatomic) IBOutlet UIView *orangeview;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    greenView =[[UIView alloc] initWithFrame:CGRectMake(100, 0,100, 200)];//X轴,Y轴,长,高
    greenView.backgroundColor =[UIColor greenColor];
    [_orangeview addSubview:greenView];     //这里是@property定义的属性用_orange,后面是对象,所以不需要
   //在orange视图上添加一个绿色视图
    UIView * yelloView=[[UIView alloc]initWithFrame:CGRectMake(100,0, 100,100)];
    yelloView.backgroundColor=[UIColor yellowColor];
    [greenView addSubview:yelloView];
    //在绿色视图上添加一个黄色师徒
}
- (IBAction)didtouch:(UITapGestureRecognizer*)sender {
    NSLog(@"汪伟,%ld",sender.state);
}
- (IBAction)longtouch:(UITapGestureRecognizer *)sender  //由于是从view控制那拖过来,类型是ID,因此state无法识别,需要告诉state
{                                                       //是UITapGestureRecognizer类型的指针
    NSLog(@"汪伟,%ld",sender.state);
}

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

@end