ios-NSMutableArray替換對象

NSMutableArray替換對象

我想要在NSMutableArray替換一個數組對象，從_alertsArray獲取了oldArray，然後修改值，用newArray替換oldArray，但是沒實現。

NSArray *oldArray = (NSArray *)[_alertsArray objectAtIndex:[indexPath row]];
NSMutableArray *newArray = [[NSMutableArray alloc] initWithArray:oldArray copyItems:YES];
[newArray replaceObjectAtIndex:3 withObject:@"YES"];
[_alertsArray replaceObjectAtIndex:[indexPath row] withObject:newArray];

最佳回答：

NSMutableArray *newArray = [_alertsArray mutableCopy];
[newArray replaceObjectAtIndex:3 withObject:@"YES"];
_alertsArray = newArray;