NSdate 与 NSString转换

date类型转换为字符串，格式可以在这个格式字符串中自定义，例如加上时分秒

-(NSString*)nsdateToString:(NSDate *)date
{
NSDateFormatter *dateFormat=[[NSDateFormatter alloc]init];
[dateFormat setDateFormat:@"yyyy-MM-dd"];
NSString* string=[dateFormat stringFromDate:date];
NSLog(@"%@",string);
return string;
}

字符串类型转换为NSDate

- (NSDate *)dateFromString:(NSString *)dateString
 {
 NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
 [dateFormatter setDateFormat: @"yyyy-MM-dd"];
 NSDate *destDate= [dateFormatter dateFromString:dateString];
 return destDate;
 }