时间格式的字符串更改格式
NSDateFormatter *dateFormat=[[NSDateFormatter alloc]init];
[dateFormat setDateFormat:@"yyyy-MM-dd HH:mm:ss"]; //这个格式字符串对应的格式，一定要对应，不然取不到date
NSDate *date=[dateFormat dateFromString:self.model.birthday];
NSDateFormatter *formater=[[NSDateFormatter alloc]init];
[formater setDateFormat:@"yyyy-MM-dd"];
NSString *currentDateStr = [formater stringFromDate:date];
self.receiveData=currentDateStr;
