iOS - 时间换算

换算时间

//字符串转成整型
int pTime = [topicItem.videotime intValue] ;
  int hour = pTime / 3600;
  int minutes = (pTime / 60) % 60 ;
  int second = pTime % 60 ;
  NSString * time = [NSString  stringWithFormat:@"%02d:%02d:%02d" ,hour,minutes,second] ;

获取当前的时间和计算任意时间离当前时间的时间差

 // 当前日期
NSDate *nowDate = [NSDate date];

// 计算出相差多少秒
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
formatter.dateFormat = @"yyyy-MM-dd HH-mm-ss";
NSDate *creatData = [formatter dateFromString:(任意时间)];
// 将传入的字符串转化成时间
NSTimeInterval timeInterva = [nowDate timeIntervalSinceDate: creatData]; 

把数据转换成当前时刻

NSDate  *date = [NSDate dateWithTimeIntervalSince1970:数据];// 时间戳字符串
NSTimeZone *zone = [NSTimeZone systemTimeZone];
NSInteger interval = [zone secondsFromGMTForDate: date];
NSDate *localeDate = [date  dateByAddingTimeInterval: interval];

刚刚，几分钟前，几小时前，昨天，前天

//时间
NSString *createdTimeStr = @"2017-01-01 21:05:10";
//把字符串转为NSdate
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
NSDate *timeDate = [dateFormatter dateFromString:createdTimeStr];
//得到与当前时间差
NSTimeInterval  timeInterval = [timeDate timeIntervalSinceNow];
timeInterval = -timeInterval;
long temp = 0;
NSString *result;
if (timeInterval < 60) {
    result = [NSString stringWithFormat:@"刚刚"];
}else if((temp = timeInterval/60) < 60){
    result = [NSString stringWithFormat:@"%ld分钟前",temp];
}else if((temp = timeInterval/3600) > 1 && (temp = timeInterval/3600) <24){
    result = [NSString stringWithFormat:@"%ld小时前",temp];
}else if ((temp = timeInterval/3600) > 24 && (temp = timeInterval/3600) < 48){
    result = [NSString stringWithFormat:@"昨天"];
}else if ((temp = timeInterval/3600) > 48 && (temp = timeInterval/3600) < 72){
    result = [NSString stringWithFormat:@"前天"];
}else{
    result = createdTimeStr;
}
 
NSLog(@"%@",result);

封装一些简单实用的方法，NSDate的分类

import "NSDate+Extension.h"

#import <Foundation/Foundation.h>

@interface NSDate (Extension)

/**
 *传入时间与当前时间的差值
 */
- (NSDateComponents *)deltaFrom:(NSDate *)date;

/**
 *是否为今年
 */
- (BOOL)isThisYear;

/**
 *是否为今天
 */
- (BOOL)isToday;

/**
 *是否为昨天
 */
- (BOOL)isYestoday;

/**
 *返回只有年月日的时间
 */
- (NSDate *)dateWithYMD;

import "NSDate+Extension.m"

#import "NSDate+Extension.h"

@implementation NSDate (Extension)

/**
 传入时间与当前时间的差值
 */
- (NSDateComponents *)detalFrom:(NSDate *)date{
    
    NSCalendar *calendar = [NSCalendar currentCalendar];
    NSCalendarUnit unit = NSCalendarUnitDay | NSCalendarUnitMonth | NSCalendarUnitYear | NSCalendarUnitHour | NSCalendarUnitMinute | NSCalendarUnitSecond;
    //self 发帖时间
    NSDateComponents *compas = [calendar components:unit fromDate:self toDate:date options:0];
    
    return compas;
}

/**
 *是否为今年
 */
- (BOOL)isThisYear{
    
    // 日历
    NSCalendar *calendar = [NSCalendar currentCalendar];
    NSInteger nowYear = [calendar component:NSCalendarUnitYear fromDate:[NSDate date]];
    NSInteger selfYear = [calendar component:NSCalendarUnitYear fromDate:self];
    return nowYear == selfYear;
}

/**
 *是否为今天
 */
// 第一种方法
//- (BOOL)isToday{
//    // 日历
//    NSCalendar *calendar = [NSCalendar currentCalendar];
//    NSCalendarUnit unit = NSCalendarUnitDay | NSCalendarUnitMonth | NSCalendarUnitYear;
//    NSDateComponents *nowComp = [calendar components:unit fromDate:[NSDate date]];
//    NSDateComponents *selfComp = [calendar components:unit fromDate:self];

//    return nowComp.year == selfComp.year
//    && nowComp.month == selfComp.month
//    && nowComp.day == selfComp.day;
//}

// 第二种方法
//- (BOOL)isToday{
//    NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
//    formatter.dateFormat = @"yyyy-MM-dd";
//    NSString *nowString = [formatter stringFromDate:[NSDate date]];
//    NSString *selfString = [formatter stringFromDate:self];
//    return nowString == selfString;
//}

// 第三种
- (BOOL)isToday{
// 日历
    NSCalendar *calendar = [NSCalendar currentCalendar];
    return [calendar isDateInToday:self] ;
}

/**
 *是否为昨天
 */
- (BOOL)isYestoday{
//    NSDate *nowDate = [[NSDate date] dateWithYMD];
//    NSDate *selfDate = [self dateWithYMD];
//    // 获得nowDate和selfDate的差距、
//    NSCalendar *calendar = [NSCalendar currentCalendar];
//    NSDateComponents *cmps = [calendar components:NSCalendarUnitDay fromDate:selfDate toDate:nowDate options:0];
//    return cmps.day == 1;
    
    // 日历
    NSCalendar *calendar = [NSCalendar currentCalendar];
    return [calendar isDateInYesterday:self] ;
    
}

/**
 *返回只有年月日的时间
 */
- (NSDate *)dateWithYMD{
    NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
    formatter.dateFormat = @"yyyy-MM-dd";
    NSString *selfString = [formatter stringFromDate:self];
    return [formatter dateFromString:selfString];
}

@end

实际应用

//对时间的处理逻辑
    
    //获取发贴时间的年份先进行年份的对比。   ---》 用到了日历对象NSCalendar  类扩展中
    
    NSString *creatTimeStr = topicItem.create_time ;
    
    //发帖日期字符串转为发帖日期对象
    NSDateFormatter *datefmt = [[NSDateFormatter alloc]init] ;
    datefmt.dateFormat = @"yyyy-MM-dd HH:mm:ss" ;//格式不能错误
    //转为发帖日期对象
    NSDate *creatTime = [datefmt dateFromString:creatTimeStr] ;//本质也是遍历和拼接
    
    //获取发帖日期与当前日期的差值
    NSDate *nowData = [NSDate date] ;
    NSDateComponents *detalCmp = [creatTime detalFrom:nowData] ;
    NSLog(@"%@",detalCmp) ;
    if ([creatTime isThisYear]) { // 是今年
        if ([creatTime isToday]) { // 是今天
            if (detalCmp.minute >= 1) { // 几分钟前
                creatTimeStr = [NSString stringWithFormat:@"%ld分钟前",detalCmp.minute] ;
            }else if (detalCmp.hour >= 1){ // 几小时前
                creatTimeStr = [NSString stringWithFormat:@"%ld小时前",detalCmp.hour] ;
            }else{ // 刚刚
                creatTimeStr = @"刚刚";
            }
        }else if ([creatTime isYestoday]){ // 是昨天
            NSLog(@"不是今天") ;
            datefmt.dateFormat = @"昨天 HH:mm" ;
            creatTimeStr = [datefmt stringFromDate:creatTime] ;
        }else{   //昨天之前
            NSLog(@"是昨天") ;
            datefmt.dateFormat = @"MM-dd HH:mm" ;
            creatTimeStr = [datefmt stringFromDate:creatTime] ;
        }
    }else{
        creatTimeStr = topicItem.create_time ;
    }
    
    self.creatTime.font = [UIFont systemFontOfSize:15.f] ;
    
    self.creatTime.text = creatTimeStr ;
    
    
}

常用的类型转换（简述）

数据类型转换：
1）int-->NSNumber:numberWithInt
   NSNumber *numObj = [NSNumber numberWithInt: 2];
2）NSNumber-->nsinteger:integerValue
3）string -->double:initWithString
4）CGFloat --> dobule:initWithFloat,decimalobj doubleValue
5）NSString与NSInteger的相互转换
   int pTime = [topicItem.videotime intValue] ;  或者 integerValue