定义具有许多(或无限)参数的方法

Question

该initWithObjects:方法NSArray采用的参数不确定的列表:

NSMutableArray *array = [[NSMutableArray alloc]initWithObjects:(id), ..., nil

我该如何定义自己的方法呢？

- (void)CustomMethod:????? <= want to take infinite arguments {

}

Answer 1

"无限参数"是变量参数,使用它们的方法称为可变参数方法.您可以使用与NSMutableArray示例相同的方式定义它们.Apple的技术问答有一个如何实现它的例子.

- (void) appendObjects:(id) firstObject, ...
{
    id eachObject;
    va_list argumentList;
    if (firstObject) // The first argument isn't part of the varargs list,
    {                                   // so we'll handle it separately.
        [self addObject: firstObject];
        va_start(argumentList, firstObject); // Start scanning for arguments after firstObject.
        while ((eachObject = va_arg(argumentList, id))) // As many times as we can get an argument of type "id"
            [self addObject: eachObject]; // that isn't nil, add it to self's contents.
        va_end(argumentList);
    }
}

nil争论的原因是您知道何时到达列表的末尾.像功能NSLog和printf不需要的最后一个参数是nil因为它可以在格式字符串计数符的数量(%d,%s等...)