iOS 数组方法大全

一.不可变数组

 //创建空数组
NSArray *arr = [[NSArray alloc]init];
//对象方法创建数组 以nil结束
NSArray *arr1= [NSArray alloc]initWithObjects:@"sun",@"is",@"girl", nil];
//用已有数组创建新数组
NSArray *arr2 = [[NSArray array]initWithArray:arr];
//通过类方法创建数组
NSArray *arr3 = [NSArray arrayWithArray:arr2];
//类方法创建空数组
NSArray *arr4 = [NSArray array];

1.不可变数组的方法

//取一个元素
NSArray *arr = @[@"sun",@"is",@"a",@"smilling",@"girl"];
NSString *string = [arr objectAtIndex:2];
//取第一个元素
NSString *first = [arr firstObject];
//取最后一个元素
NSString *last = [arr lastObject];
//简单方法取一个元素
NSString *str2 = arr[3];

//取多个
//NSIndexSet:是一个索引集合，原理上与数组类似，只不过这是一个无序的
NSIndexSet *set4 = [[NSIndexSet alloc]initWithIndexesInRange:NSMakeRange(1, 2)];
NSArray *arr3 = [array1 objectAtIndex:set4];

//简单方法截取多个元素
NSArray *arr4 = [array1 subarrayWithRange:NSMakeRange(2, 3)];

//for in 快速遍历  只针对数组来说，in的前面是数组中的元素， in后面是要遍历的集合（数组／字典）
for (NSString *str in array1) {
  NSLog(@"%@",str);
}

二.可变数组

1.创建

//创建空数组
NSMutableArray *mutArray = [NSMutableArray array];
//capacity
NSMutableArray *mutAr = [NSMutableArray arrayWithCapacity:100];
NSMutableArray *mutcap = [[NSMutableArray alloc]initWithCapacity:100];
NSArray *array = @[@"dskfj",@"df",@"sd",@"f"];
NSMutableArray *mutarr3 = [[NSMutableArray alloc]initWithArray:array];
//通过类方法
NSMutableArray *mutarr5 = [NSMutableArray arrayWithObjects:@"sdj",@"dsf", nil];

2.增删改查

//增
NSMutableArray *mutArray1 = [NSMutableArray arrayWithObjects:@"sunck", @"is", @"a", @"nice", @"man", nil];
//增加到数组的结尾
//1、增加一个元素
[mutArray1 addObject:@"!"];
NSLog(@"mutArray1-1 = %@", mutArray1);
//2、增加多个
[mutArray1 addObjectsFromArray:@[@"Oh", @"right"]];
NSLog(@"mutArray1-2 = %@", mutArray1);
//在数组中增加

//注意：如果数组中有多个相同的元素，那么会全部删除
//1、删除一个元素
//1.1按元素删除  注意：如果数组中有多个相同的元素，那么会全部删除
 NSMutableArray *mutArray = [NSMutableArray arrayWithObjects:@"sd",@"sun",@"id",@"good",@"girl", nil];
[mutArray removeObject:@"sd"];

  //1.2按下标删除
 [mutArray removeObjectAtIndex:3];

  //1.3删除最后一个
  [mutArray removeLastObject];

  //删除多个
  //在range范围内删除第一个参数的中的数据
  NSIndexSet *set4 = [[NSIndexSet alloc]initWithIndexesInRange:NSMakeRange(5, 2)];
  [mutArray removeObjectsAtIndexes:set4];

  //删除全部
  [mutArray removeAllObjects];

3.字符传切割

//切割
NSString *str = @"sdjfkjdsjf#*sjkd#*skdud#*skudjhfksd#*";
NSArray *array = [str componentsSeparatedByString:@"#*"];

//一字符集合中的字符切割
NSString *str1 =@"skjdfsl!skljdfkds* smjdfjs*JHhndnf.sdfs";
NSCharacterSet *set = [NSCharacterSet characterSetWithCharactersInString:@"!*,."];
NSArray *arr1 = [str1 componentsSeparatedByCharactersInSet:set];

//组合
//将数组中的字符传元素按照某种规则组合成一个新的字符串
NSArray *arr3 = @[@"sdjn",@"sun",@"id",@"sd"];
NSString *str4 = [arr3 componentsJoinedByString:@"!!"];

4.简单数据封装存储在字典和数字中

//NSNumber:专门用于封装简单数据类型的类
//Why:在OC中数组、字典等存储工具里面只能存储对象，所以需要封装
//封装成对象
int a = 10;
int b = 20;

NSNumber *aNum = [[NSNumber alloc] initWithInt:a];
NSNumber *bNum = [[NSNumber alloc] initWithInt:b];

NSLog(@"aNum = %@", aNum);
NSLog(@"bNum = %@", bNum);

//存入数组
NSArray *array = @[aNum, bNum];

//比较大小
NSComparisonResult result = [aNum compare:bNum];

//解封
int c = [aNum intValue];
int d = [bNum intValue];

5.数组排序

//数组的排序
//写排序的标准(方法)：（升序排、降序排），写在数组元素的类里面
//NSOrderedDescending  NSOrderedAscending
//带SEL的排序
[arr  sortUsingSelector:NSOrderedDescending];

数组排序1

void arraySort1() {  
    NSArray *array = [NSArray arrayWithObjects:@"2", @"3", @"1", @"4", nil nil];  
  
    // 返回一个排好序的数组，原来数组的元素顺序不会改变  
    // 指定元素的比较方法：compare:  
    NSArray *array2 = [array sortedArrayUsingSelector:@selector(compare:)];  
    NSLog(@"array2:%@", array2);  
}  

数组排序2

void arraySort2() {  
  Student *stu1 = [Student studentWithFirstname:@"MingJie" lastname:@"Li"];  
  Student *stu2 = [Student studentWithFirstname:@"LongHu" lastname:@"Huang"];  
  Student *stu3 = [Student studentWithFirstname:@"LianJie" lastname:@"Li"];  
  Student *stu4 = [Student studentWithFirstname:@"Jian" lastname:@"Xiao"];  
  NSArray *array = [NSArray arrayWithObjects:stu1,stu2,stu3, stu4, nil nil];  
  // 指定排序的比较方法  
  NSArray *array2 = [array sortedArrayUsingSelector:@selector(compareStudent:)];  
  NSLog(@"array2:%@", array2);  
}  
- (NSComparisonResult)compareStudent:(Student *)stu {  
  // 先按照姓排序  
  NSComparisonResult result = [self.lastname compare:stu.lastname];  
  // 如果有相同的姓，就比较名字  
  if (result == NSOrderedSame) {  
      result = [self.firstname compare:stu.firstname];  
  }  
  return result;  
}  

数组排序3

void arraySort3() {  
  Student *stu1 = [Student studentWithFirstname:@"MingJie" lastname:@"Li"];  
  Student *stu2 = [Student studentWithFirstname:@"LongHu" lastname:@"Huang"];  
  Student *stu3 = [Student studentWithFirstname:@"LianJie" lastname:@"Li"];  
  Student *stu4 = [Student studentWithFirstname:@"Jian" lastname:@"Xiao"];  
  NSArray *array = [NSArray arrayWithObjects:stu1,stu2,stu3, stu4, nil nil];  
  
  // 利用block进行排序  
  NSArray *array2 = [array sortedArrayUsingComparator:^NSComparisonResult(Student *obj1, Student *obj2) {  
     // 先按照姓排序  
     NSComparisonResult result = [obj1.lastname compare:obj2.lastname];  
     // 如果有相同的姓，就比较名字  
     if (result == NSOrderedSame) {  
         result = [obj1.firstname compare:obj2.firstname];  
     }  
       
     return result;  
  }];  
  
  NSLog(@"array2:%@", array2);  
}  

数组排序4-高级排序

void arraySort4() {  
  Student *stu1 = [Student studentWithFirstname:@"MingJie" lastname:@"Li" bookName:@"book1"];  
  Student *stu2 = [Student studentWithFirstname:@"LongHu" lastname:@"Huang" bookName:@"book2"];  
  Student *stu3 = [Student studentWithFirstname:@"LianJie" lastname:@"Li" bookName:@"book2"];  
  Student *stu4 = [Student studentWithFirstname:@"Jian" lastname:@"Xiao" bookName:@"book1"];  
  NSArray *array = [NSArray arrayWithObjects:stu1,stu2,stu3, stu4, nil nil];  
  
  // 1.先按照书名进行排序  
  // 这里的key写的是@property的名称  
  NSSortDescriptor *bookNameDesc = [NSSortDescriptor sortDescriptorWithKey:@"book.name" ascending:YES];  
  // 2.再按照姓进行排序  
  NSSortDescriptor *lastnameDesc = [NSSortDescriptor sortDescriptorWithKey:@"lastname" ascending:YES];  
  // 3.再按照名进行排序  
  NSSortDescriptor *firstnameDesc = [NSSortDescriptor sortDescriptorWithKey:@"firstname" ascending:YES];  
  // 按顺序添加排序描述器  
  NSArray *descs = [NSArray arrayWithObjects:bookNameDesc, lastnameDesc, firstnameDesc, nil nil];  
  
  NSArray *array2 = [array sortedArrayUsingDescriptors:descs];  
  
  NSLog(@"array2:%@", array2);  
}