IOS ID生成器

//
//  IdGenerator.m
//  Copyright (c) 2014年 青岛拓宇网络科技有限公司. All rights reserved.
//

#import "IdGenerator.h"

static long long time_stamp = 0;
static long long time_stamp_now = 0;
static NSMutableArray *temp = NULL;
static NSNumber *random_n = NULL;
static NSLock *theLock = NULL;

@implementation IdGenerator

/*
*  获取下一个Id
*/
+ (long long)next{

if(theLock == NULL)
theLock = [[NSLock alloc]init];

if(temp == NULL)
temp = [[NSMutableArray alloc]init];

@synchronized(theLock){
time_stamp_now = [[NSDate date] timeIntervalSince1970];
if(time_stamp_now != time_stamp){
//清空缓存，更新时间戳
[temp removeAllObjects];
time_stamp = time_stamp_now;
}

//判断缓存中是否存在当前随机数
while ([temp containsObject:(random_n = [NSNumber numberWithLong:arc4random() % 8999 + 1000])])
;

if ([temp containsObject:random_n]) {
return -1;
}

[temp addObject:[NSNumber numberWithLong:[random_n longValue]]];
}

return (time_stamp * 10000) + [random_n longValue];
}

@end