ios 小知识仅供参考

 //计算字符串中单词的个数 1     + (int)countWords:(NSString*)s
 2     {
 3         int i,n=[s length],l=0,a=0,b=0;
 4         unichar c;
 5         for(i=0;i<n;i++){
 6             c=[s characterAtIndex:i];
 7             if(isblank(c))
 8             {
 9                 b++;
10             }else if(isascii(c))
11             {
12                 a++;
13             }else
14             {
15                 l++;
16             }
17         }
18         if(a==0 && l==0)
19         {
20             return 0;
21         }
22         return l+(int)ceilf((float)(a+b)/2.0);
23     }  

//获取系统语言+ (NSString *)getLocalLanguage
{
    NSString *language = [[[NSUserDefaults standardUserDefaults] objectForKey:@"AppleLanguages"] objectAtIndex:0];
    return language;
} 

//获取本月，本周，本季度第一天的时间戳+ (unsigned long long)getFirstDayOfWeek:(unsigned long long)timestamp
{
    NSDate *now = [NSDate dateWithTimeIntervalSince1970:timestamp];
    NSCalendar *cal = [NSCalendar currentCalendar];
    NSDateComponents *comps = [cal
                               components:NSYearCalendarUnit| NSMonthCalendarUnit| NSWeekCalendarUnit | NSWeekdayCalendarUnit |NSWeekdayOrdinalCalendarUnit
                               fromDate:now];
    if (comps.weekday <2)
    {
        comps.week = comps.week-1;
    }
    comps.weekday = 2;
    NSDate *firstDay = [cal dateFromComponents:comps];
    return [firstDay timeIntervalSince1970];
}

+ (unsigned long long)getFirstDayOfQuarter:(unsigned long long)timestamp
{
    NSDate *now = [NSDate dateWithTimeIntervalSince1970:timestamp];
    NSCalendar *cal = [NSCalendar currentCalendar];
    NSDateComponents *comps = [cal
                               components:NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit
                               fromDate:now];
    if (comps.month <=3)
    {
        comps.month =  1;
    }
    else if(comps.month<=6)
    {
        comps.month =  4;
    }
    else if(comps.month<=9)
    {
        comps.month =  7;
    }
    else if(comps.month<=12)
    {
        comps.month =  10;
    }

    comps.day = 1;
    NSDate *firstDay = [cal dateFromComponents:comps];
    return [firstDay timeIntervalSince1970]*1000;
}

+ (unsigned long long)getFirstDayOfMonth:(unsigned long long)timestamp
{
    NSDate *now = [NSDate dateWithTimeIntervalSince1970:timestamp/1000];
    NSCalendar *cal = [NSCalendar currentCalendar];
    NSDateComponents *comps = [cal
                               components:NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit
                               fromDate:now];
    comps.day = 1;
    NSDate *firstDay = [cal dateFromComponents:comps];
    return [firstDay timeIntervalSince1970]*1000;
}

//监测网络状态 1 - (void)reachabilityChanged:(NSNotification *)note {
 2     Reachability* curReach = [note object];
 3     NSParameterAssert([curReach isKindOfClass: [Reachability class]]);
 4     NetworkStatus status = [curReach currentReachabilityStatus];
 5
 6     if (status == NotReachable)
 7     {
 8
 9     }
10     else if(status == kReachableViaWiFi)
11     {
12
13     }
14     else if(status == kReachableViaWWAN)
15     {
16
17     }
18
19 }
20
21 - (void)setNetworkNotification
22 {
23     [[NSNotificationCenter defaultCenter] addObserver:self
24                                              selector:@selector(reachabilityChanged:)
25                                                  name: kReachabilityChangedNotification
26                                                object: nil];
27     _hostReach = [[Reachability reachabilityWithHostName:@"http://www.baidu.com"] retain];
28     [_hostReach startNotifier];
29 }

//16进制颜色转UIColor 1 + (UIColor *)colorWithHex:(NSString *)hex {
 2     // Remove `#` and `0x`
 3     if ([hex hasPrefix:@"#"]) {
 4         hex = [hex substringFromIndex:1];
 5     } else if ([hex hasPrefix:@"0x"]) {
 6         hex = [hex substringFromIndex:2];
 7     }
 8
 9     // Invalid if not 3, 6, or 8 characters
10     NSUInteger length = [hex length];
11     if (length != 3 && length != 6 && length != 8) {
12         return nil;
13     }
14
15     // Make the string 8 characters long for easier parsing
16     if (length == 3) {
17         NSString *r = [hex substringWithRange:NSMakeRange(0, 1)];
18         NSString *g = [hex substringWithRange:NSMakeRange(1, 1)];
19         NSString *b = [hex substringWithRange:NSMakeRange(2, 1)];
20         hex = [NSString stringWithFormat:@"%@%@%@%@%@%@ff",
21                r, r, g, g, b, b];
22     } else if (length == 6) {
23         hex = [hex stringByAppendingString:@"ff"];
24     }
25
26     CGFloat red = [[hex substringWithRange:NSMakeRange(0, 2)] _hexValue] / 255.0f;
27     CGFloat green = [[hex substringWithRange:NSMakeRange(2, 2)] _hexValue] / 255.0f;
28     CGFloat blue = [[hex substringWithRange:NSMakeRange(4, 2)] _hexValue] / 255.0f;
29     CGFloat alpha = [[hex substringWithRange:NSMakeRange(6, 2)] _hexValue] / 255.0f;
30
31     return [UIColor colorWithRed:red green:green blue:blue alpha:alpha];
32 }