前言
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背景
每天的iOS开发过程中经常会出现Check一些逻辑是否每天仅发生一次,一般我们的通用是用NSDate判断是否是今天,然后对NSDate做持久化存储 eg: MMKV、或者NSUserDefault,但随着工程的日渐庞大,我们逐渐关注一些细节和代码 的耗时.
首先来看一下几种不同的逻辑判断NSDateisToday的代码实现
- 1.系统NSCalendar日历
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NSDate *date = [NSDate date]; //这里取当前日期,正常应该做为参数传入NSDate
BOOL inToday = [[NSCalendar currentCalendar] isDateInToday:date]
- 2.增加更多参数调用NSCalendar
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- (BOOL)isToday {
NSCalendar *cal = [NSCalendar currentCalendar];
NSDateComponents *components = [cal components:(NSCalendarUnitEra|NSCalendarUnitYear|NSCalendarUnitMonth|NSCalendarUnitDay) fromDate:[NSDate date]];
NSDate *today = [cal dateFromComponents:components];
components = [cal components:(NSCalendarUnitEra|NSCalendarUnitYear|NSCalendarUnitMonth|NSCalendarUnitDay) fromDate:self];
NSDate *otherDate = [cal dateFromComponents:components];
return [today isEqualToDate:otherDate];
}
- 3.通过比较时间
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- (BOOL)isTodayWithDate:(NSDate *)date {
NSDate *selfBegin = [self dateByBeginDay];
NSDate *dateBegin = [date dateByBeginDay];
if (fabs([selfBegin timeIntervalSinceDate:dateBegin]) < 1.0e-6) {
return YES;
}
return NO;
}
- (NSDate *)dateByBeginDay {
//前一天的结束 16:00为结束 8小时时区 今天开始 也就是说 前一天的00:00:00
unsigned int flags = NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay | NSCalendarUnitHour | NSCalendarUnitMinute | NSCalendarUnitSecond;
NSDateComponents *parts = [[NSCalendar currentCalendar] components:flags fromDate:self];
[parts setHour:0];
[parts setMinute:0];
[parts setSecond:0];
return [[NSCalendar currentCalendar] dateFromComponents:parts];
}
这几种都是检测是否是当天的代码
故事的开始
今天工作中Review代码 对NSDate的检查判断是否是today的耗时问题产生了分歧,工程师解决问题的方式很简单,实践代码证明是否耗时.
我选中了 第一种和第三种做测试.代码如下:
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2023-02-13 19:59:08.855078+0800 NSDateSpeedDemo[1837:197213] NSCalendar耗时:0.011064
2023-02-13 19:59:11.108141+0800 NSDateSpeedDemo[1837:197213] NSDate (YZUtils)耗时:0.030793
完整的代码如下:
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- (IBAction)didSysDateClick:(id)sender {
NSDate *date = [NSDate date];
CFTimeInterval startTime = CACurrentMediaTime();
for (int i = 0; i < 1000; i++) {
__unused BOOL inToday = [[NSCalendar currentCalendar] isDateInToday:date];
}
CFTimeInterval endTime = CACurrentMediaTime();
NSString *log = [NSString stringWithFormat:@"NSCalendar耗时:%f",endTime - startTime];
NSLog(@"%@", log);
self.l1.text = log;
}
- (IBAction)didOnCusDateClick:(id)sender {
NSDate *date = [NSDate date];
CFTimeInterval startTime = CACurrentMediaTime();
for (int i = 0; i < 1000; i++) {
__unused BOOL inToday = [date isTodayWithDate:date];
self.l2.text = [NSString stringWithFormat:@"SysDate:%d",i];
}
CFTimeInterval endTime = CACurrentMediaTime();
NSString *log = [NSString stringWithFormat:@"NSDate (YZUtils)耗时:%f",endTime - startTime];
NSLog(@"%@", log);
self.l2.text = log;
}
总结
这时间上还是差至少1x左右,如果频繁的操作确实会影响一些性能.