什么是Objective-C语法,椭圆样式点符号？"......"

Question

我在Joe Hewitt的Three20源代码中注意到了这一点,之前我从未在Objective-C中看到过这种特殊的语法.甚至不确定如何在适当的Google搜索中引用它.

来自TTTableViewDataSource:

+ (TTSectionedDataSource*)dataSourceWithObjects:(id)object,... {

"......"就是把我扔掉的原因.我假设它是一种枚举形式,可以提供可变数量的参数.如果是,这个运营商的官方名称是什么,我在哪里可以参考它的文档？

非常感谢你.

Answer 1

它是一种可变方法,意味着它需要可变数量的参数. 这个页面很好地演示了如何使用它:

#import <Cocoa/Cocoa.h>

@interface NSMutableArray (variadicMethodExample)

- (void) appendObjects:(id) firstObject, ...;  // This method takes a nil-terminated list of objects.

@end

@implementation NSMutableArray (variadicMethodExample)

- (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);
  }
}