IOS学习笔记之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);