关于NSMutableArray removeObject

有三个NSString，

    NSString *str1 = @"123";

    NSString *str2 = [NSString stringWithFormat:@"123"];

    NSMutableString *str3 = [NSMutableStringstringWithFormat:@"123"];

    NSLog(@"str1 = %p , str2 = %p, str3 = %p", str1, str2, str3);

　　

    NSLog(@"str1 = %d , str2 = %d, str3 = %d", [str1 hash], [str2 hash], [str3 hash]);

 

打印的内存地址分别为 

str1 = 0x58b0 , str2 = 0x8d376e0, str3 = 0x8d3e380

hash 值都为 

487557729

    NSMutableArray *array = [@[str1, str2, str3, @"1234"] mutableCopy];

    [array removeObject:str1];

    NSLog(@"array = %@", array);

  array = (

    1234

)

可以证明 removeobject 是根据hash值的映射，只要hash值相同，在NSMutableArray removeObject 的时候都会被remove掉