IOS 判断两个时间相隔多少天

- (NSString *)intervalFromLastDate: (NSString *) dateString1toTheDate:(NSString *) dateString2

{

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

[date setDateFormat:@"yyyy-MM-dd"];

NSDate *d1=[date dateFromString:dateString1];

NSTimeInterval late1=[d1 timeIntervalSince1970]*1;

NSDate *d2=[date dateFromString:dateString2];

NSTimeInterval late2=[d2 timeIntervalSince1970]*1;

NSTimeInterval cha=late2-late1;

NSString *timeString=@"";

NSString *house=@"";

NSString *min=@"";

NSString *sen=@"";

sen = [NSString stringWithFormat:@"%d", (int)cha%60];

sen=[NSString stringWithFormat:@"%@", sen];

min = [NSString stringWithFormat:@"%d", (int)cha/60%60];

min=[NSString stringWithFormat:@"%@", min];

house = [NSString stringWithFormat:@"%d", (int)cha/3600];

house=[NSString stringWithFormat:@"%@", house];

timeString=[NSString stringWithFormat:@"差小时:%@-----分:%@------秒:%@",house,min,sen];

return timeString;

}