[oc学习笔记]数组

    NSArray *arr = @[@"dsd",@"43"];    // 在原有数组后面加一个元素，原数组不变，产生新数组    NSArray *arr1 = [arr arrayByAddingObject:@"saddas"];    //在原数组后面加一个数组，产生新数组，原数组不变    NSArray *atrr2 = [arr arrayByAddingObjectsFromArray:arr];    //取出原数组制定范围元素    NSArray *aa = [arr subarrayWithRange:NSMakeRange(2,2)];            //选择器排序    //一定要写selector 常用比较方法为compare    NSArray *arr3 = [arr sortedArrayUsingSelector:@selector(compare:)];    //代码块排序    NSArray *arr4 = [arr sortedArrayUsingComparator:^NSComparisonResult(id obj1, id obj2) {      return [obj1 compare:obj2];    }];    //比较描述器排序    //常用于多个条件的比较    //存放比较描述器    NSSortDescriptor *sort1 = [NSSortDescriptor sortDescriptorWithKey:@"ss" ascending:YES];    NSArray *d = @[sort1];    NSArray *arr5 = [arr sortedArrayUsingDescriptors:d];        //可变数组定义    NSMutableArray *mu1 = [NSMutableArray array];    NSMutableArray *mu2 = [NSMutableArray arrayWithCapacity:10];    //可变数组尾部加元素    [mu1 addObject:@"sds"];    //可变数组尾部家数组    [mu1 addObjectsFromArray:@[@"d",@"ffgf"]];    //在什么位置插入    [mu1 insertObject:@"dd" atIndex:1];    //移除    [mu1 removeAllObjects];//全部    [mu2 removeLastObject];//最后    [mu2 removeObject:@"ff"];//特定元素    [mu2 removeObjectAtIndex:2];//特定位置    [mu2 removeObject:@"d" inRange:NSMakeRange(2, 1)];//特定范围的特定元素    //用指定字符替换制定位置的元素    [mu2 replaceObjectAtIndex:2 withObject:@"ff"];    //交换两个位置的元素    [mu2 exchangeObjectAtIndex:1 withObjectAtIndex:2];    //注意可变字符串与不可变字符串的排序方法的写法不同，此处不一一列举

　　　　 
    NSArray *aa = [[NSArray alloc]init];    NSArray *aaa = [NSArray array];    //声明单个内容数组    NSArray *aaaa = [NSArray arrayWithObject:@"sd"];    //声明多个内容数组    NSArray *arr = [NSArray arrayWithObjects:@"SDS",@"Dsad", nil];    //数组的长度    NSLog(@"%zi",arr.count);    //数组中某个下标对应的对象    NSLog(@"%@",[arr objectAtIndex:1]);    //数组中最后一个对应的对象    NSLog(@"%@",[arr lastObject]);    //数组中某个元素对应的下标    NSLog(@"%zi",[arr indexOfObject:@"Dsad"]);    //写入文件    NSString *path = @"/Users/XuLee/Desktop/oc/abc.txt";    [arr writeToFile:path atomically:YES];    //读文件必须是特定格式    NSString *ff = [NSArray arrayWithContentsOfFile:path];    //把数组的对象中间加一个东西连接成一个字符串    NSString *fg = [arr componentsJoinedByString:@"-"];    //数组的遍历    //普通遍历方式    for (int i = 0; i < arr.count; i++) {      id obj = [arr objectAtIndex:i];      NSLog(@"%@",obj);    }    //快速遍历    for (id obj in arr ) {      NSLog(@"%@",obj);    }    //代码块遍历    [arr enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop)    // obj为元素 idx 为下标 stop相当于break stop为yes时 循环会结束    {      NSLog(@"%@",obj);      //stop 赋值形式为 ＊stop ＝ yes or no    }];    //迭代器遍历    //将数组中各个元素装入迭代器中    NSEnumerator * vv = [arr objectEnumerator];    id obj = nil;    while (obj = [vv nextObject]) {      NSLog(@"%@",obj);    }    //反向迭代    NSEnumerator *vvv = [arr reverseObjectEnumerator];    while (obj = [vvv nextObject]) {      NSLog(@"%@",obj);    }    //让数组统一调用某方法        Student *stu1 = [[Student alloc]init];    stu1.name = @"fff";    Student *stu2 = [[Student alloc]init];    stu2.name = @"hhh";    NSArray *aee = [NSArray arrayWithObjects:stu1,stu2,nil];    [aee makeObjectsPerformSelector:@selector(sayHi)];        //让数组统一调用某一带参数的方法        [aee makeObjectsPerformSelector:@selector(study:) withObject:@"math"];    

-(NSString *)description{  NSString *aa = [NSString stringWithFormat:@"%@",_name];  return aa;}-(void)sayHi{  NSLog(@"my name %@",_name);}-(void)study:(NSString *)ss{  NSLog(@"%@ study %@",_name,ss);}

@property (nonatomic,strong)NSString *name;-(void)sayHi;-(void)study:(NSString *)ss;

原标题：[oc学习笔记]数组

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