iOS生成随机字符串

/**
 生成随机字母
 @param number  需要的个数
 @return 生成的字符串
 */
+ (NSString *)randomString:(NSInteger)number;

+ (NSString *)randomString:(NSInteger)number {
    
    NSString *ramdom;
    NSMutableArray *array = [NSMutableArray array];
    for (int i = 1; i ; i ++) {
        int a = (arc4random() % 122);
        if (a > 96) {
            char c = (char)a;
            [array addObject:[NSString stringWithFormat:@"%c",c]];
            if (array.count == number) {
                break;
            }
        } else continue;
    }
    ramdom = [array componentsJoinedByString:@""];
    return ramdom;
    
}