认识NS_REQUIRES_NIL_TERMINATION

NS_REQUIRES_NIL_TERMINATION是系统中多参数传值的一个宏，用于编译时非nil结尾的检查。

找到了官网上的一个栗子：

#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);
  }
}

@end
           

感觉还不错呦，自己也可以模仿着写一个的：

ZW_UIKit.h

#import <Foundation/Foundation.h>

@interface ZW_UIKit : NSObject

+ (NSArray *)getMoreArguments:(NSString *)strs,...NS_REQUIRES_NIL_TERMINATION;

@end
           

ZW_UIKit.m

#import "ZW_UIKit.h"

@implementation ZW_UIKit

#pragma mark - 获取多参数
+ (NSArray *)getMoreArguments:(NSString *)strs,...
{
    va_list args;
    va_start(args, strs);
    NSMutableArray *allArray = [NSMutableArray array];
    for (NSString *str = strs; str != nil; str = va_arg(args,NSString*)) {
        [allArray addObject:str];
    }
    va_end(args);
    return allArray.copy;
}


@end
           

调用：

[ZW_UIKit getMoreArguments:@"arg1",@"arg2",@"arg3", nil];