NSArray 基本用法

　 NSString *string1 = @"two";

        NSString *string2 = @"one";

        //创建数组

        NSArray *array1 = [NSArray arrayWithObjects:string1,string2,nil];

        NSArray *array2 = [NSArray arrayWithArray:array1];

        //创建数组只包含已有数组的一部分

        NSRange range = NSMakeRange(0, 2);

        NSArray *subArray = [array1 subarrayWithRange:range];

        //array的长度

        int arrayLength = [array1 count];

        //访问数组中特定位置的一个对象

        NSString *string = [array1 objectAtIndex:0];

        //是否包含指定对象

        BOOL isInArray = [array1 containsObject:string1];

        //对象在数组中的位置

        int index = [array1 indexOfObject:string1];

        

        //遍历一个数组中的值

        for(NSString *obj in array1)

        {

            NSLog(@"%@",obj);

        }

        //反向遍历一个数组的值

        for(NSString *objfan in [array1reverseObjectEnumerator])

        {

            NSLog(@"%@",objfan);

        }

        //对字符串的重新排序(有点问题)

        //[array1 sortUsingSelector:@selector(localizedCaseInsensitiveCompare:)];

        //NSLog(@"array1 = %@",array1);

        //创建动态数组

        NSMutableArray *myarray = [[NSMutableArray alloc]initWithObjects:string1,string2, nil];

        NSString *string3 = @"Three";

        //向动态数组中添加

        [myarray addObject:string3];

        [myarray addObject:string2];

        [myarray insertObject:string3 atIndex:0];

        [myarray insertObject:string2 atIndex:1];

        //替换

        [myarray replaceObjectAtIndex:1withObject:string3];

        //删除

        [myarray removeObject:string3];

        //删除特定位置对象

        [myarray removeObjectAtIndex:0];

        //删除几个对象

        [myarray removeObjectsInRange:range];

        //删除所有对象

        [myarray removeAllObjects];

#pragma mark 数组的内存管理
void arrayMemory() {
    // 1
    Student *stu1 = [[Student alloc] init];
    Student *stu2 = [[Student alloc] init];
    Student *stu3 = [[Student alloc] init];
    
    NSLog(@"stu1:%zi", [stu1 retainCount]);
    
    // 当把一个对象塞进数组中时，这个对象的计数器会加1，也就是说数组会对它做一次retain操作
    // 2
    NSArray *array = [[NSArray alloc] initWithObjects:stu1, stu2, stu3, nil];
    
    NSLog(@"stu1:%zi", [stu1 retainCount]);
    
    NSLog(@"count=%zi", array.count);
    
    // 1
    [stu1 release];
    [stu2 release];
    [stu3 release];
    
    // 数组被销毁的时候，会对内部的所有元素都做一次release操作
    // 0
    [array release];
}

#pragma mark 给数组里面的元素发送消息
void arrayMessage() {
    Student *stu1 = [Student student];
    Student *stu2 = [Student student];
    Student *stu3 = [Student student];
    
    NSArray *array = [NSArray arrayWithObjects:stu1, stu2, stu3, nil];
    // 让数组里面的所有对象都调用test方法
    // [array makeObjectsPerformSelector:@selector(test)];
    [array makeObjectsPerformSelector:@selector(test2:) withObject:@"123"];
}

#pragma mark 派生出新的数组
void arrayNew() {
    NSArray *array = [NSArray arrayWithObjects:@"1", @"2", nil];
    
    NSArray *array2 = [array arrayByAddingObject:@"3"];
    
    NSArray *array3 = [array arrayByAddingObjectsFromArray:[NSArray arrayWithObjects:@"4", @"5", nil]];
    
    NSLog(@"array:%@", array);
    NSLog(@"array2:%@", array2);
    NSLog(@"array3:%@", array3);
    
    
    NSArray *array4 = [NSArray arrayWithObjects:@"1", @"2", @"3", @"4", nil];
    NSRange range = NSMakeRange(1, 2);
    NSArray *array5 = [array4 subarrayWithRange:range];
    NSLog(@"array5:%@", array5);
}

#pragma mark 数组的其他用法
void arrayOther() {
    NSArray *array = [NSArray arrayWithObjects:@"1", @"2", @"3", @"4", nil];
    // 1-2-3-4
    // 利用分隔符-拼接所有的数组元素
    NSString *str = [array componentsJoinedByString:@"-"];
    NSLog(@"%@", str);
    
    // 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];
    NSLog(@"array2:%@", array2);
}

#pragma mark 数组排序1
void arraySort1() {
    NSArray *array = [NSArray arrayWithObjects:@"2", @"3", @"1", @"4", 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];
    
    // 指定排序的比较方法
    NSArray *array2 = [array sortedArrayUsingSelector:@selector(compareStudent:)];
    
    NSLog(@"array2:%@", array2);
}

#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];
    
    // 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];
    
    // 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];
    
    NSArray *array2 = [array sortedArrayUsingDescriptors:descs];
    
    NSLog(@"array2:%@", array2);
}