NSString2015-09-30转化为NSData

NSString *dateString=@"2015-09-30";

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

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

[dateFormatter setTimeZone:[NSTimeZone timeZoneWithAbbreviation:@"UTC"]];

 myData = [dateFormatter dateFromString:dateString];