OC4(数组)

1，不可变数组

1，数组是有序的，下标从0开始，只能存放对象类型的元素，与NSNumber、NSValue相联系

2，不可变数组的创建方法

  NSArray *array1 = [[NSArray alloc]initWithObjects:@"zhonger",@"honghuang",@"taixu",@"zhili",nil];//nil不是对象，指示标记，告诉编译器，数组赋值结束

笑笑语法

NSArray *array3 = @[@"shuishen",@"huangshenme",@"youyisi",@"qiuxiang",@12];

3，数组的两个核心方法count、objectAtIndex

4，判断数组中是否包含某个元素

BOOL isTure =[array2 containsObject:@"zhuba"];

5，获取某个元素所在的数组下标

NSUInteger index = [array2 indexOfObject:@"bada"];

6，通过数组实现分割字符串和拼接字符串

NSString *str = @"zhonger m 19 f";

    NSArray *resultArray =[str componentsSeparatedByString:@" "];

 

 NSArray *array = @[@"bada",@"qiuxiang",@"zaiyiqi"];

    NSString *resultStr = [array componentsJoinedByString:@"💗"];

 

 

2、可变数组

初始化方法

NSMutableArray *mArr = [[NSMutableArray alloc] initWithCapacity:0];

便利构造器

NSMutableArray *mArr1 = [NSMutableArray arrayWithCapacity:0];

字面量创建方式

NSMutableArray *mArr2 = [@[@"zhonger",@"dada",@"zhuzhu",@"linlin"] mutableCopy];

    NSLog(@"mArr2 is %@",mArr2);

 

//往可变数组中添加元素 addObject:

[mArr addObject:@"123"];

NSLog(@"mArr is %@",mArr);

   

//往可变数组的制定位置，插入一个新元素

[mArr2 insertObject:@"qiuxiang" atIndex:2];

NSLog(@"mArr2 is %@",mArr2);

   

//移除可变数组中的某一个元素

[mArr2 removeObject:@"zhonger"];//删除指定元素

[mArr2 removeObjectAtIndex:3];//删除某个下标的元素

NSLog(@"mArr2 is %@",mArr2);

   

[mArr2 removeLastObject];//删除数组中的最后一个元素

NSLog(@"mArr2 is %@",mArr2);

   

[mArr2 removeAllObject];//删除数组中的所有元素

NSLog(@"mArr2 is %@",mArr2);

   

//替换可变数组中的某个元素

[mArr2 replaceObjectAtIndex:0 withObject:@"zhonger"];

[mArr2 replaceObjectAtIndex:1 withObject:@"taixu"];

NSLog(@"mArr2 is %@",mArr2);

   

//交换可变数组中两个元素的位置

[mArr2 exchangeObjectAtIndex:0 withObjectAtIndex:1];

NSLog(@"mArr2 is %@",mArr2);