ObjectC快速入门教程(3)---数组和字典

一.不可变数组

1.创建

总结:OC中数组是对象的有序集合，数组存储的是对象的地址(对象的引用),不可变数组一旦被创建，不可以继续添加,删除,或者修改；数组中的元素可以为不同类型的对象.

  NSArray *array1 = @[@"one", @"two", @"three", @"four", [NSNumber numberWithInt:123]];        NSLog(@"array1 = %@", array1);        NSArray *array1 = @[@"one", @"two", @"three", @"four", [NSNumber numberWithInt:123]];        NSLog(@"array1 = %@", array1);        NSArray *array2 = [[NSArray alloc]init]; //空数组        NSLog(@"array2 = %@", array2);        NSArray *arryy3 = [[NSArray alloc]initWithObjects:@"one", @"two", nil];        NSLog(@"array3 = %@", arryy3);

2.数组的访问

 NSLog(@"array1[1] = %@", [array1 objectAtIndex:1]);        NSLog(@"array1[1] = %@", array1[1]);        NSLog(@"cnt = %li", [array1 count]);        //获取元素在数组中第一次出现的位置        NSInteger index = [array1 indexOfObject:@"two"];        NSLog(@"index = %li", index);        NSLog(@"first = %@", [array1 firstObject]); //第一个元素        NSLog(@"last = %@", [array1 lastObject]);   //最后一个元素

3.数组的比较

      //数组比较        NSArray *array10 = @[@"one", @"two", @"three"];        NSArray *array11 = [NSArray arrayWithObjects:@"one", @"two1", nil];        BOOL ret = [array10 isEqualToArray:array11]; //判断两个数组是否相等        if(ret){            NSLog(@"两个数组相等");        }else{            NSLog(@"两个数组不想等");        }        //返回数组中第一个想等的元素        id obj = [array10 firstObjectCommonWithArray:array11];        NSLog(@"%@", obj);

4.数组排序

//数组排序,前提：数组中的元素是相同类型的        NSArray *sortArray = [array10 sortedArrayUsingSelector:@selector(compare:)];//@selector大于0时进行交换        NSLog(@"%@", sortArray);

5.数组添加

 //数组添加        NSArray *array12 = [array10 arrayByAddingObject:@"five"];        NSLog(@"array12 = %@", array12);

6.指定范围内的提取

 //提取指定范围内的数组        NSArray *array13 = [array10 subarrayWithRange:NSMakeRange(2, 2)];        NSLog(@"array13 = %@", array13);        //NSIndexSet 下表集合类        NSMutableIndexSet *index2 = [NSMutableIndexSet indexSetWithIndex:1];        [index2 addIndex:3];        NSArray *array14 = [array10 objectsAtIndexes:index2];        NSLog(@"array14 = %@", array14);

7.字符串分割成数组

 NSString* str = @"I :am :good :boy";        NSArray* array15 = [str componentsSeparatedByString:@" :"];        NSLog(@"array15 = %@", array15);        NSArray *array16 = [str componentsSeparatedByCharactersInSet:[NSCharacterSet characterSetWithCharactersInString:@" :"]];        NSLog(@"array16 = %@", array16);

注意:componentsSeparatedByString和componentsSeparatedByCharactersInSet的区别,参考,前者以字符串整体作为分隔符，后者以字符串集合中的每一个字符作为分隔符.

8.数组元素的拼接

 NSArray *array = @[@"one", @"two", @"three"];        NSString *arrayStr = [array componentsJoinedByString:@" "];        NSLog(@"arrayStr = %@", arrayStr);

9.数组遍历

        //方法1,通过数组元素下标        for(NSInteger i = 0; i < [array count]; i++){//            NSLog(@"%@", [array objectAtIndex:i]);        }        //方法2，通过枚举器        NSEnumerator *enumerator = [array reverseObjectEnumerator];        id obj2 = nil;        while(obj2 = [enumerator nextObject]){//            NSLog(@"%@", obj2);        }        //方法3，快速枚举法        for(id obj3 in array){            NSLog(@"%@", obj3);        }

二.可变数组

1.创建添加

NSMutableArray *marray = [[NSMutableArray alloc]initWithObjects:@"one", @"two", @"three", nil];        [marray addObject:@"four"];        [marray addObjectsFromArray:@[@"five", @"six"]]; //增加        [marray insertObject:@"zero" atIndex:0];    //插入        NSLog(@"%@", marray);

2.替换指定位置下标元素

  [marray setArray:@[@"1", @"2"]];        NSLog(@"%@", marray);        [marray replaceObjectAtIndex:1 withObject:@"123"];        NSLog(@"%@", marray);

3.交换

   [marray exchangeObjectAtIndex:0 withObjectAtIndex:1];        NSLog(@"%@", marray);

4.删除

三.字典对象

1.创建,添加

NSDictionary *dict0 = @{@"one":@"1",@"two":@"2"}; //前面是key后面是value        NSLog(@"%@", dict0);        NSDictionary *dict = [NSDictionary dictionaryWithObjectsAndKeys:@"one",@"1",@"two", @"2",nil];//前面是value后面是key        NSLog(@"%@", dict);        NSMutableDictionary *dict1 = [NSMutableDictionary dictionaryWithDictionary:dict0];        [dict1 setValue:@"4" forKey:@"four"]; //增加一个元素        NSInteger count = [dict1 count]; //个数        NSLog(@"%@", dict1);        id obj33 = [dict1 objectForKey:@"one"]; //根据key得到value        NSArray *keyArray = [dict1 allKeys]; //获得所有key        NSArray *value = [dict1 allValues];  //获得所有value        BOOL isEqual = [dict1 isEqualToDictionary:dict];        if(isEqual){            NSLog(@"相等");        }else{            NSLog(@"不相等");        }        NSLog(@"%@", value);        //增加键值对        [dict1 addEntriesFromDictionary:@{@"hello":@"hello123"}];

注意事项:在字典对象中，key的值是唯一的，一旦有了一个key，是不能覆盖的。

2.字典的遍历

    //方法1，枚举法        NSEnumerator *keyEnumerator = [dict1 keyEnumerator];        id obj44 = nil;        while(obj44 = [keyEnumerator nextObject]){            NSLog(@"key = %@ value = %@", obj44, [dict1 valueForKey:obj44]);        }        //方法2，快速枚举法        for(id obj55 in dict1){            NSLog(@"key = %@ value = %@", obj55, [dict1 objectForKey:obj55]);        }