NSData NSDate NSString NSArray NSDictionary 相互转换

//	NSData  NSDate NSString NSArray NSDictionary json
  NSString *string = @"hello word";
  NSData *data = [string dataUsingEncoding:NSUTF8StringEncoding];
  NSArray *array = [NSArray arrayWithObjects:@"1",@"2",@"3",nil];
  NSString *dateString = @"19891123";
  NSDictionary *dic = [NSDictionary dictionaryWithObjectsAndKeys:
             @"hello", @"word",
             @"chen", @"lu",
             @"jin", @"mei",
             @"cerastes", @"hehe",nil];

//	NSString to NSData
  NSData *string2data = [string dataUsingEncoding:NSUTF8StringEncoding];
  NSLog(@"%@",string2data);
//	NSData to NSString
  NSString *data2String = [[NSString alloc]initWithData:data encoding:NSUTF8StringEncoding];
  NSLog(@"dataString = %@",data2String);
  
//	NSArray to NSData
  
  NSData *arry2data = [NSKeyedArchiver archivedDataWithRootObject:array];
//	NSData to NSArray
  NSArray *data2arry = [NSKeyedUnarchiver unarchiveObjectWithData:arry2data];
  NSLog(@"%@  /n %@",arry2data,data2arry);
  
//	NSString to NSDate
  NSDate *string2date = [self convertDateFromString:dateString withFormattre:@"yyyyMMdd"];
  NSLog(@"date = %@",string2date);
  
//	NSDate to NSString
  NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
  [dateFormatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
  NSString *date2string = [dateFormatter stringFromDate:[NSDate date]];
  NSLog(@"%@", date2string);
  

//   NSArray to NSString
  
  
  NSString *arry2String = [array componentsJoinedByString:@" "];
  
  NSLog(@"string = %@",arry2String);
  
  
//	NSString to NSArray
  NSArray *string2Arry = [arry2String componentsSeparatedByString:@" "];
  NSLog(@" %@",string2Arry);
  

  
//	NSDictionary to NSData:
  NSMutableData *dic2data = [[NSMutableData alloc] init];
  NSKeyedArchiver *archiver = [[NSKeyedArchiver alloc] initForWritingWithMutableData:dic2data];
  [archiver encodeObject:dic forKey:@"Some Key Value"];
  [archiver finishEncoding];
  NSLog(@"%@",dic2data);
  
//	NSData to NSDictionary
  NSKeyedUnarchiver *unarchiver = [[NSKeyedUnarchiver alloc] initForReadingWithData:dic2data];
  NSDictionary *data2dic = [unarchiver decodeObjectForKey:@"Some Key Value"];
  [unarchiver finishDecoding];
  NSLog(@"%@",data2dic);
  
  
//	NSDictionary to NSString
  NSString *dic2string=[dic JSONRepresentation]; //这个方法是SBJson类库里的，需要导入SBJson.h
  NSLog(@"%@",dic2string);
  
//	NSString to NSDictionary
  NSError *error = nil;
  NSDictionary *string2dic = [NSJSONSerialization JSONObjectWithData: [dic2string dataUsingEncoding:NSUTF8StringEncoding]
                  options: NSJSONReadingMutableContainers
                    error: &error];
  NSLog(@"%@",string2dic);

// 将数组转为json 序列化
NSArray *body = @[@"1",@"2"];
NSData *data = [NSJSONSerialization dataWithJSONObject:body

                                        options:NSJSONWritingPrettyPrinted
                                          error:nil];