iOS实用小工具

.计算时间间隔多少秒,可以使用到计算程序代码执行时间

方式1:

    CFTimeInterval begin = CFAbsoluteTimeGetCurrent();
    for (NSInteger i = 0; i< 5000; i++) {
        NSLog(@"123456");
    }
    CFTimeInterval end = CFAbsoluteTimeGetCurrent();

方式2:

    NSDate *begin = [NSDate date];
    for (NSInteger i = 0; i< 5000; i++) {
        NSLog(@"123456");
    }
    NSDate *end = [NSDate date];
    
    NSLog(@"%f",[end timeIntervalSinceDate:begin]);

方式3:

NSTimeInterval start = [[NSDate date] timeIntervalSince1970]*1;
    for (NSInteger i = 0; i< 5000; i++) {
        NSLog(@"------%ld",i);
    }
    NSTimeInterval end = [[NSDate date] timeIntervalSince1970]*1;
    NSTimeInterval value = end - start;
    int second = (int)value %60;//秒
    int minute = (int)value /60%60;
    int house = (int)value / (24 * 3600)%3600;
    int day = (int)value / (24 * 3600);
    NSString *str;
    if (day != 0) {
        str = [NSString stringWithFormat:@"耗时%d天%d小时%d分%d秒",day,house,minute,second];
    }else if (day==0 && house != 0) {
        str = [NSString stringWithFormat:@"耗时%d小时%d分%d秒",house,minute,second];
    }else if (day== 0 && house== 0 && minute!=0) {
        str = [NSString stringWithFormat:@"耗时%d分%d秒",minute,second];
    }else{
        str = [NSString stringWithFormat:@"耗时%d秒",second];
    }
    return str;

计算N天前日期

/**
 获取指定天数前的日期

 @param beforeDay 多少天之前
 */
- (NSString *)getDateBeforeDay:(NSInteger)beforeDay{
    NSDateFormatter *dateFormat = [[NSDateFormatter alloc]init ] ;
    [dateFormat setDateFormat:@"yyyy-MM-dd"] ;
    
    NSString *localDateStr = @"";
    BOOL isSystem = YES;//[ZTEConfigrationList currAppTimeZone]; 是否是系统时区
    if (!isSystem) {
        //获取本地时间
        [dateFormat setTimeZone:[NSTimeZone timeZoneWithName:@"Asia/Hong_Kong"]];
        localDateStr = [dateFormat stringFromDate:[NSDate date]];
    } else {
        localDateStr = [dateFormat stringFromDate:[NSDate date]] ;
    }
    
    NSDate *date = [dateFormat dateFromString:localDateStr];
    
    //计算day天以前时间
    NSDate *someDaysAgoDate = [NSDate dateWithTimeInterval:-(beforeDay-1) * 24 * 60 * 60 sinceDate:date];
    return [dateFormat stringFromDate:someDaysAgoDate];
}

当前2017-09-16 运行结果: 2017-09-18