iOS规范化时间格式，object-C计算指定时间与当前的时间差

#import <Foundation/Foundation.h>

@interface LuDate : NSDate
+(NSString *) compareCurrentTime:(NSString*) strDate;
@end

/**
 
 * 计算指定时间与当前的时间差
 
 * @param compareDate   某一指定时间
 
 * @return 多少(秒or分or天or月or年)+前 (比如，3天前、10分钟前)
 
 */

+(NSString *) compareCurrentTime:(NSString*) strDate

{
    
    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    
    [dateFormatter setDateFormat: @"yyyy-MM-dd HH:mm:ss"];
    
    NSDate *compareDate= [dateFormatter dateFromString:strDate];
    
    
    NSTimeInterval  timeInterval = [compareDate 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分前",temp];
        
    }
    
    
    
    else if((temp = temp/60) <24){
        
        result = [NSString stringWithFormat:@"%ld小前",temp];
        
    }
    
    
    
    else if((temp = temp/24) <30){
        
        result = [NSString stringWithFormat:@"%ld天前",temp];
        
    }
    
    
    
    else if((temp = temp/30) <12){
        
        result = [NSString stringWithFormat:@"%ld月前",temp];
        
    }
    
    else{
        
        temp = temp/12;
        
        result = [NSString stringWithFormat:@"%ld年前",temp];
        
    }
    
    
    
    return  result;
    
}
@end