1.date转字符串

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

//设置日期格式

[formattersetDateFormat:@"yyyy-MM-dd HH:mm:ss"];

//当前日期

NSDate*currentDate =[NSDate date];

NSString*currentDateString =[formatter stringFromDate:currentDate];

NSLog(@"%@",currentDateString);

2.字符串转化为date

NSDateFormatter* dateFormat = [[NSDate Formatteralloc]init];//实例化一个NSDateFormatter对象

[dateFormat setDateFormat:@"yyyy-MM-dd HH:mm:ss"];//设定时间格式,这里可以设置成自己需要的格式

NSDate*date =[dateFormat dateFromString:@"1990-01-02 00:00:01"];