ios数组操作集合，数组排序

来源：互联网发布：飞升元神数据编辑：程序博客网时间：2024/05/18 01:01

1.数组的基本用法

    int count = [array count];//个数      // 判断是否包含了某个元素      if ([array containsObject:@"a"]) {          NSLog(@"包含了字符串a");      }      NSString *last = [array lastObject];最后一个元素      NSString *str = [array objectAtIndex:1];根据索引获取数组中的元素      int index = [array indexOfObject:@"c"];获取指定元素的索引      // 让数组里面的所有对象都调用test方法，123为参数      NSArray *array = [NSArray arrayWithObjects:stu1, stu2, stu3, nil nil];      [array makeObjectsPerformSelector:@selector(test2:) withObject:@"123"];      NSArray *array = [NSArray arrayWithObjects:@"1", @"2", @"3", @"4", nil nil];      // 1-2-3-4      // 利用分隔符-拼接所有的数组元素      NSString *str = [array componentsJoinedByString:@"-"];      // 将一个数组写入文件（生成的是一个xml文件）      NSString *path = @"/Users/apple/Desktop/array.xml";      [array writeToFile:path atomically:YES];      path = @"/Users/apple/Desktop/array.txt";      // 从文件中读取数组内容（文件有严格的格式要求）      NSArray *array2 = [NSArray arrayWithContentsOfFile:path];

2.数组遍历

    #pragma mark 遍历数组1      void arrayFor1() {          NSArray *array = [NSArray arrayWithObjects:stu1, @"1", @"2", @"3", nil nil];          int count = array.count;          for (int i = 0; i<count; i++) {              id obj = [array objectAtIndex:i];          }      }            #pragma mark 遍历数组2 快速遍历      void arrayFor2() {          Student *stu1 = [Student student];          NSArray *array = [NSArray arrayWithObjects:stu1, @"1", @"2", @"3", nil nil];          int i =0;          for (id obj in array) {              NSLog(@"%i-%@", i, obj);              i++;          }      }            #pragma mark 遍历数组3      void arrayFor3() {          Student *stu1 = [Student student];          NSArray *array = [NSArray arrayWithObjects:stu1, @"1", @"2", @"3", nil nil];          [array enumerateObjectsUsingBlock:           ^(id obj, NSUInteger idx, BOOLBOOL *stop) {              NSLog(@"%i-%@", idx, obj);               // 如果索引为1，就停止遍历               if (idx == 1) {                   // 利用指针修改外面BOOL变量的值                   *stop = YES;               }          }];      }            #pragma mark 遍历数组4      void arrayFor4() {          Student *stu1 = [Student student];          NSArray *array = [NSArray arrayWithObjects:stu1, @"1", @"2", @"3", nil nil];          // 获取数组的迭代器          // NSEnumerator *enumerator = [array objectEnumerator];          // 反序迭代器（从尾部开始遍历元素）          NSEnumerator *enumerator = [array reverseObjectEnumerator];          // allObjects是取出没有被遍历过的对象          NSArray *array2 = [enumerator allObjects];          NSLog(@"array2:%@", array2);          // 获取下一个需要遍历的元素          id obj = nil;          while (obj = [enumerator nextObject]) {              NSLog(@"obj=%@", obj);          }      }

3.数组排序

#pragma mark 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);  }    #pragma mark 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;  }    #pragma mark 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);  }    #pragma mark 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);  }

4.数组去重
利用NSSet的AllObjects方法

这种方法更快，利用NSSet不会添加重复元素的特性。不过去重的数组没有进行排序，如果需要排序，可以使用NSSortDescriptor类。

示例代码：

NSArray *arr = @[@111,@222,@111];

NSSet *set = [NSSetsetWithArray:arr];

NSLog(@"%@",[setallObjects]);

输出结果为：

2013-05-21 12:06:26.508 test1[4547:c07] (

111,

222

)

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