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
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