ios开发处理服务器返回的时间字符串

#import <Foundation/Foundation.h>

void other();
void string2date();

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        other();
        
        string2date();
    }
    return 0;
}

void other()
{
    // 获得NSCalendar
    NSCalendar *calendar = nil;
    if ([NSCalendar respondsToSelector:@selector(calendarWithIdentifier:)]) {
        calendar = [NSCalendar calendarWithIdentifier:NSCalendarIdentifierGregorian];
    } else {
        calendar = [NSCalendar currentCalendar];
    }
    
    NSDateFormatter *fmt = [[NSDateFormatter alloc] init];
    fmt.dateFormat = @"yyyy-MM-dd HH:mm:ss";
    
    NSLog(@"%zd", [calendar isDateInToday:[fmt dateFromString:@"2015-11-10 01:09:56"]]);
    
}

void dateCompare3()
{
    NSDateFormatter *fmt = [[NSDateFormatter alloc] init];
    fmt.dateFormat = @"yyyy-MM-dd HH:mm:ss";

    // 时间字符串
    NSString *createdAtString = @"2015-11-01 09:10:05";
    NSDate *createdAtDate = [fmt dateFromString:createdAtString];

    // 其他时间
    NSString *otherString = @"2015-10-31 08:56:45";
    NSDate *otherDate = [fmt dateFromString:otherString];

    // 获得NSCalendar
    NSCalendar *calendar = nil;
    
    if ([NSCalendar respondsToSelector:@selector(calendarWithIdentifier:)]) {
        calendar = [NSCalendar calendarWithIdentifier:NSCalendarIdentifierGregorian];
    } else {
        calendar = [NSCalendar currentCalendar];
    }

    // 获得日期之间的间隔
    NSCalendarUnit unit = NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay | NSCalendarUnitHour | NSCalendarUnitMinute | NSCalendarUnitSecond;
    NSDateComponents *cmps = [calendar components:unit fromDate:createdAtDate toDate:otherDate options:0];
    
    NSLog(@"%@", cmps);
}

void dateCompare2()
{
    // 时间字符串
    NSString *createdAtString = @"2015-11-20 09:10:05";
    NSDateFormatter *fmt = [[NSDateFormatter alloc] init];
    fmt.dateFormat = @"yyyy-MM-dd HH:mm:ss";
    NSDate *createdAtDate = [fmt dateFromString:createdAtString];

    // 手机当前时间
    //    NSDate *nowDate = [NSDate date];

    // 获得createdAtDate和nowDate的时间间隔(间隔多少秒)
    //    NSTimeInterval interval = [nowDate timeIntervalSinceDate:createdAtDate];
    NSTimeInterval interval = [createdAtDate timeIntervalSinceNow];
    
    NSLog(@"%f", interval);
}

void dateCompare()
{
    // 时间字符串
    NSString *createdAtString = @"2015-11-20 11:10:05";
    NSDateFormatter *fmt = [[NSDateFormatter alloc] init];
    fmt.dateFormat = @"yyyy-MM-dd HH:mm:ss";
    NSDate *createdAtDate = [fmt dateFromString:createdAtString];

    // 手机当前时间
    NSDate *nowDate = [NSDate date];

    /**
     NSComparisonResult的取值
     NSOrderedAscending = -1L, // 升序, 越往右边越大
     NSOrderedSame,  // 相等
     NSOrderedDescending // 降序, 越往右边越小
     */
    // 获得比较结果(谁大谁小)
    NSComparisonResult result = [nowDate compare:createdAtDate];
    if (result == NSOrderedAscending) { // 升序, 越往右边越大
        NSLog(@"createdAtDate > nowDate");
    } else if (result == NSOrderedDescending) { // 降序, 越往右边越小
        NSLog(@"createdAtDate < nowDate");
    } else {
        NSLog(@"createdAtDate == nowDate");
    }
}

/**
 *  日期元素 : 年月日时分秒
 */
void getComponentsOfDate3()
{
    // 时间字符串
    NSString *string = @"2015-11-20 09:10:05";

    // 日期格式化类
    NSDateFormatter *fmt = [[NSDateFormatter alloc] init];
    // 设置日期格式(为了转换成功)
    fmt.dateFormat = @"yyyy-MM-dd HH:mm:ss";

    // NSString * -> NSDate *
    NSDate *date = [fmt dateFromString:string];

    // 利用NSCalendar处理日期
    NSCalendar *calendar = [NSCalendar currentCalendar];

    NSCalendarUnit unit = NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay | NSCalendarUnitHour | NSCalendarUnitMinute | NSCalendarUnitSecond;
    NSDateComponents *cmps = [calendar components:unit  fromDate:date];

    //    NSLog(@"%zd %zd %zd", cmps.year, cmps.month, cmps.day);
    NSLog(@"%@", cmps);
}

/**
 *  日期元素 : 年月日时分秒
 */
void getComponentsOfDate2()
{
    // 时间字符串
    NSString *string = @"2015-11-20 09:10:05";

    // 日期格式化类
    NSDateFormatter *fmt = [[NSDateFormatter alloc] init];
    // 设置日期格式(为了转换成功)
    fmt.dateFormat = @"yyyy-MM-dd HH:mm:ss";

    // NSString * -> NSDate *
    NSDate *date = [fmt dateFromString:string];

    // 利用NSCalendar处理日期
    NSCalendar *calendar = [NSCalendar currentCalendar];
    NSInteger month = [calendar component:NSCalendarUnitMonth fromDate:date];
    NSInteger hour = [calendar component:NSCalendarUnitHour fromDate:date];
    NSInteger minute = [calendar component:NSCalendarUnitMinute fromDate:date];
    

    NSLog(@"%zd %zd %zd", month, hour, minute);
}

/**
 *  日期元素 : 年月日时分秒
 */
void getComponentsOfDate()
{
    // 时间字符串
    NSString *string = @"2015-11-20 09:10:05";
    

    NSString *month = [string substringWithRange:NSMakeRange(5, 2)];

    NSLog(@"%@", month);
}

void date2string()
{
    NSDate *date = [NSDate date];

    NSDateFormatter *fmt = [[NSDateFormatter alloc] init];
    fmt.dateFormat = @"yyyy年MM月dd号 HH:mm:ss";

    NSString *string = [fmt stringFromDate:date];
    
    NSLog(@"----%@+++++", string);
    
}

void string2date4()
{
    // 时间戳 : 从1970年1月1号 00:00:00开始走过的毫秒数

    // 时间字符串 - 时间戳
    NSString *string = @"1745645645645";
    
    NSTimeInterval second = string.longLongValue / 1000.0;

    // 时间戳 -> NSDate *
    NSDate *date = [NSDate dateWithTimeIntervalSince1970:second];
    
    NSLog(@"%@", date);
}

void string2date3()
{
    // 时间字符串
    NSString *string = @"Tue May 31 17:46:55 +0800 2011";

    // 日期格式化类
    NSDateFormatter *fmt = [[NSDateFormatter alloc] init];
    fmt.dateFormat = @"EEE MMM dd HH:mm:ss Z yyyy";
    // fmt.dateFormat = @"EEE MMM dd HH:mm:ss ZZZZ yyyy";
    // 设置语言区域(因为这种时间是欧美常用时间)
    fmt.locale = [[NSLocale alloc] initWithLocaleIdentifier:@"en_US"];

    NSLog(@"%@", [fmt dateFromString:string]);
}

void string2date2()
{
    // 时间字符串
    NSString *string = @"11月-20号/2015年 09-10:05秒";

    // 日期格式化类
    NSDateFormatter *fmt = [[NSDateFormatter alloc] init];
    fmt.dateFormat = @"MM月-dd号/yyyy年 HH-mm:ss秒";

    NSLog(@"%@", [fmt dateFromString:string]);
}

void string2date()
{
    // 时间字符串
    NSString *string = @"2015-11-20 09:33:22";

    // 日期格式化类
    NSDateFormatter *fmt = [[NSDateFormatter alloc] init];
    // 设置日期格式(为了转换成功)
    fmt.dateFormat = @"yyyy-MM-dd HH:mm:ss";

    // NSString * -> NSDate *
    NSDate *date = [fmt dateFromString:string];
    
    NSString *newStr = [fmt stringFromDate:date];

    NSLog(@"%@", date);
    NSLog(@"%@", newStr);
    
}

 总结：

## NSDateFormatter的作用

- NSString * -> NSDate *

```obj

- (nullable NSDate *)dateFromString:(NSString *)string;

```

- NSDate * -> NSString *

```objc

- (NSString *)stringFromDate:(NSDate *)date;

```

## 常见的日期格式

- http://www.cnblogs.com/mailingfeng/archive/2011/07/28/2120422.html

## NSString * -> NSDate *

- 2015-11-20 09:10:05

```objc

// 时间字符串

NSString *string = @"2015-11-20 09:10:05";

// 日期格式化类

NSDateFormatter *fmt = [[NSDateFormatter alloc] init];

// 设置日期格式(为了转换成功)

fmt.dateFormat = @"yyyy-MM-dd HH:mm:ss";

// NSString * -> NSDate *

NSDate *date = [fmt dateFromString:string];

NSLog(@"%@", date);

```

- 11月-20号/2015年 09-10:05秒

```objc

// 时间字符串

NSString *string = @"11月-20号/2015年 09-10:05秒";

// 日期格式化类

NSDateFormatter *fmt = [[NSDateFormatter alloc] init];

fmt.dateFormat = @"MM月-dd号/yyyy年 HH-mm:ss秒";

NSLog(@"%@", [fmt dateFromString:string]);

```

- Tue May 31 17:46:55 +0800 2011

```objc

// 时间字符串

NSString *string = @"Tue May 31 17:46:55 +0800 2011";

// 日期格式化类

NSDateFormatter *fmt = [[NSDateFormatter alloc] init];

fmt.dateFormat = @"EEE MMM dd HH:mm:ss Z yyyy";

// fmt.dateFormat = @"EEE MMM dd HH:mm:ss ZZZZ yyyy";

// 设置语言区域(因为这种时间是欧美常用时间)

fmt.locale = [[NSLocale alloc] initWithLocaleIdentifier:@"en_US"];

NSLog(@"%@", [fmt dateFromString:string]);

```

- 1745645645645

```objc

// 时间戳 : 从1970年1月1号 00:00:00开始走过的毫秒数

// 时间字符串 - 时间戳

NSString *string = @"1745645645645";

NSTimeInterval second = string.longLongValue / 1000.0;

// 时间戳 -> NSDate *

NSDate *date = [NSDate dateWithTimeIntervalSince1970:second];

NSLog(@"%@", date);

```

## NSCalendar的注意点

```objc

#define iOS(version) ([UIDevice currentDevice].systemVersion.doubleValue >= (version))

NSCalendar *calendar = nil;

if ([UIDevice currentDevice].systemVersion.doubleValue >= 8.0) {

    calendar = [NSCalendar calendarWithIdentifier:NSCalendarIdentifierGregorian];

} else {

    calendar = [NSCalendar currentCalendar];

}

NSCalendar *calendar = nil;

if ([NSCalendar respondsToSelector:@selector(calendarWithIdentifier:)]) {

    calendar = [NSCalendar calendarWithIdentifier:NSCalendarIdentifierGregorian];

} else {

    calendar = [NSCalendar currentCalendar];

}

```

## NSDate * -> NSString *

```objc

NSDate *date = [NSDate date];

NSDateFormatter *fmt = [[NSDateFormatter alloc] init];

fmt.dateFormat = @"yyyy年MM月dd号 HH:mm:ss";

NSString *string = [fmt stringFromDate:date];

```

## 获得日期元素

```objc

NSString *string = @"2015-11-20 09:10:05";

NSString *month = [string substringWithRange:NSMakeRange(5, 2)];

NSLog(@"%@", month);

```

```objc

// 时间字符串

NSString *string = @"2015-11-20 09:10:05";

// 日期格式化类

NSDateFormatter *fmt = [[NSDateFormatter alloc] init];

// 设置日期格式(为了转换成功)

fmt.dateFormat = @"yyyy-MM-dd HH:mm:ss";

// NSString * -> NSDate *

NSDate *date = [fmt dateFromString:string];

// 利用NSCalendar处理日期

NSCalendar *calendar = [NSCalendar currentCalendar];

NSInteger month = [calendar component:NSCalendarUnitMonth fromDate:date];

NSInteger hour = [calendar component:NSCalendarUnitHour fromDate:date];

NSInteger minute = [calendar component:NSCalendarUnitMinute fromDate:date];

NSLog(@"%zd %zd %zd", month, hour, minute);

```

```objc

// 时间字符串

NSString *string = @"2015-11-20 09:10:05";

// 日期格式化类

NSDateFormatter *fmt = [[NSDateFormatter alloc] init];

// 设置日期格式(为了转换成功)

fmt.dateFormat = @"yyyy-MM-dd HH:mm:ss";

// NSString * -> NSDate *

NSDate *date = [fmt dateFromString:string];

// 利用NSCalendar处理日期

NSCalendar *calendar = [NSCalendar currentCalendar];

NSCalendarUnit unit = NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay | NSCalendarUnitHour | NSCalendarUnitMinute | NSCalendarUnitSecond;

NSDateComponents *cmps = [calendar components:unit  fromDate:date];

//    NSLog(@"%zd %zd %zd", cmps.year, cmps.month, cmps.day);

NSLog(@"%@", cmps);

```

## 日期比较

```objc

// 时间字符串

NSString *createdAtString = @"2015-11-20 11:10:05";

NSDateFormatter *fmt = [[NSDateFormatter alloc] init];

fmt.dateFormat = @"yyyy-MM-dd HH:mm:ss";

NSDate *createdAtDate = [fmt dateFromString:createdAtString];

// 手机当前时间

NSDate *nowDate = [NSDate date];

/**

 NSComparisonResult的取值

 NSOrderedAscending = -1L, // 升序, 越往右边越大

 NSOrderedSame,  // 相等

 NSOrderedDescending // 降序, 越往右边越小

 */

// 获得比较结果(谁大谁小)

NSComparisonResult result = [nowDate compare:createdAtDate];

if (result == NSOrderedAscending) { // 升序, 越往右边越大

    NSLog(@"createdAtDate > nowDate");

} else if (result == NSOrderedDescending) { // 降序, 越往右边越小

    NSLog(@"createdAtDate < nowDate");

} else {

    NSLog(@"createdAtDate == nowDate");

}

```

```objc

// 时间字符串

NSString *createdAtString = @"2015-11-20 09:10:05";

NSDateFormatter *fmt = [[NSDateFormatter alloc] init];

fmt.dateFormat = @"yyyy-MM-dd HH:mm:ss";

NSDate *createdAtDate = [fmt dateFromString:createdAtString];

// 手机当前时间

//    NSDate *nowDate = [NSDate date];

// 获得createdAtDate和nowDate的时间间隔(间隔多少秒)

//    NSTimeInterval interval = [nowDate timeIntervalSinceDate:createdAtDate];

NSTimeInterval interval = [createdAtDate timeIntervalSinceNow];

NSLog(@"%f", interval);

```

```objc

NSDateFormatter *fmt = [[NSDateFormatter alloc] init];

fmt.dateFormat = @"yyyy-MM-dd HH:mm:ss";

// 时间字符串

NSString *createdAtString = @"2015-11-01 09:10:05";

NSDate *createdAtDate = [fmt dateFromString:createdAtString];

// 其他时间

NSString *otherString = @"2015-10-31 08:56:45";

NSDate *otherDate = [fmt dateFromString:otherString];

// 获得NSCalendar

NSCalendar *calendar = nil;

if ([NSCalendar respondsToSelector:@selector(calendarWithIdentifier:)]) {

    calendar = [NSCalendar calendarWithIdentifier:NSCalendarIdentifierGregorian];

} else {

#import <Foundation/Foundation.h>

//typedef enum {
//    /** 图片 */
//    XMGTopicTypePicture = 10,
//    /** 段子 */
//    XMGTopicTypeWord = 29,
//    /** 声音 */
//    XMGTopicTypeVoice = 31,
//    /** 视频 */
//    XMGTopicTypeVideo = 41,
//} XMGTopicType;

typedef NS_ENUM(NSUInteger, XMGTopicType) {
    /** 图片 */
    XMGTopicTypePicture = 10,
    /** 段子 */
    XMGTopicTypeWord = 29,
    /** 声音 */
    XMGTopicTypeVoice = 31,
    /** 视频 */
    XMGTopicTypeVideo = 41
};

@class XMGComment;

@interface XMGTopic : NSObject
/** 用户的名字 */
@property (nonatomic, copy) NSString *name;
/** 用户的头像 */
@property (nonatomic, copy) NSString *profile_image;
/** 帖子的文字内容 */
@property (nonatomic, copy) NSString *text;
/** 帖子审核通过的时间 */
@property (nonatomic, copy) NSString *created_at;
/** 顶数量 */
@property (nonatomic, assign) NSInteger ding;
/** 踩数量 */
@property (nonatomic, assign) NSInteger cai;
/** 转发分享数量 */
@property (nonatomic, assign) NSInteger repost;
/** 评论数量 */
@property (nonatomic, assign) NSInteger comment;

/** 最热评论 */
@property (nonatomic, strong) XMGComment *top_cmt;

/** 帖子类型 */
@property (nonatomic, assign) XMGTopicType type;

@end

#import "XMGTopic.h"

@implementation XMGTopic
#pragma mark - 其他
static NSDateFormatter *fmt_;
static NSCalendar *calendar_;
/**
 *  在第一次使用XMGTopic类时调用1次
 */
+ (void)initialize
{
    fmt_ = [[NSDateFormatter alloc] init];
    calendar_ = [NSCalendar calendar];
}

- (NSString *)created_at
{
    // 获得发帖日期
    fmt_.dateFormat = @"yyyy-MM-dd HH:mm:ss";
    NSDate *createdAtDate = [fmt_ dateFromString:_created_at];
    
    if (createdAtDate.isThisYear) { // 今年
        if (createdAtDate.isToday) { // 今天
            // 手机当前时间
            NSDate *nowDate = [NSDate date];
            NSCalendarUnit unit = NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay | NSCalendarUnitHour | NSCalendarUnitMinute | NSCalendarUnitSecond;
            NSDateComponents *cmps = [calendar_ components:unit fromDate:createdAtDate toDate:nowDate options:0];
            
            if (cmps.hour >= 1) { // 时间间隔 >= 1小时
                return [NSString stringWithFormat:@"%zd小时前", cmps.hour];
            } else if (cmps.minute >= 1) { // 1小时 > 时间间隔 >= 1分钟
                return [NSString stringWithFormat:@"%zd分钟前", cmps.minute];
            } else { // 1分钟 > 分钟
                return @"刚刚";
            }
        } else if (createdAtDate.isYesterday) { // 昨天
            fmt_.dateFormat = @"昨天 HH:mm:ss";
            return [fmt_ stringFromDate:createdAtDate];
        } else { // 其他
            fmt_.dateFormat = @"MM-dd HH:mm:ss";
            return [fmt_ stringFromDate:createdAtDate];
        }
    } else { // 非今年
        return _created_at;
    }
}

@end

    calendar = [NSCalendar currentCalendar];

}

// 获得日期之间的间隔

NSCalendarUnit unit = NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay | NSCalendarUnitHour | NSCalendarUnitMinute | NSCalendarUnitSecond;

NSDateComponents *cmps = [calendar components:unit fromDate:createdAtDate toDate:otherDate options:0];

NSLog(@"%@", cmps);

```

 例子：