obsidian/笔记文件/2.笔记/ios字典转字符串.md

#ios

NSMutableDictionary 是比较灵活的字典结构，完成初始化后，搭配 setObject 和 forKey 的方式，完成数据的添加； 需要注意的是，NSMutableDictionary是一个结构灵活复杂的容器，其中可能包含，其他复杂子结构，例如日期、数组队列、枚举，其他字典等； 在转字符串之前，需要先将，其他复杂子结构，完成字符串的数据转换，参考ios NSArray转字符串 和 ios日历转字符串和ios枚举转字符串； 在完成数据的填充后，通过 copy 的方式，完成从 NSMutableDictionary 到 NSDictionary 的转换

代码示例：

                
                NSMutableDictionary *questionResponsesDict = [NSMutableDictionary dictionary];
                for(NSUInteger i=0;i<[respondent.questionResponses count]-1;i++)
                {
                    SMQuestionResponse *questionResponse = respondent.questionResponses[i];
                    NSMutableDictionary *stringDict = [NSMutableDictionary dictionary];
                    
                    [stringDict setObject:questionResponse.pageID forKey:@"pageID"];
                    [stringDict setObject:questionResponse.questionID forKey:@"questionID"];
                    [stringDict setObject:questionResponse.questionValue forKey:@"questionValue"];
                    [stringDict setObject:[questionResponse.answers description] forKey:@"answers"];
                    
                    NSNumber *pageIndexNumber = @(questionResponse.pageIndex);
                    NSString *pageIndexString = [pageIndexNumber stringValue];
                    [stringDict setObject:pageIndexString forKey:@"pageIndex"];
                    
                    NSNumber *questionSurveyIndexNumber = @(questionResponse.questionSurveyIndex);
                    NSString *questionSurveyIndexString = [questionSurveyIndexNumber stringValue];
                    [stringDict setObject:questionSurveyIndexString forKey:@"questionSurveyIndex"];
                    
                    NSNumber *questionPageIndexNumber = @(questionResponse.questionPageIndex);
                    NSString *questionPageIndexString = [questionPageIndexNumber stringValue];
                    [stringDict setObject:questionPageIndexString forKey:@"questionPageIndex"];
                    
                    NSDictionary *nsDict = [stringDict copy];
                    
                    NSNumber *index = @(i);
                    NSString *indexString = [index stringValue];
                    [questionResponsesDict setObject:nsDict forKey:indexString];
                    
                }

然后，通过 NSJSONSerialization dataWithJSONObject 的方式，完成从字典，到NSData 数据类的，格式转换； 其中 options:0 指的是，会去掉 json 数据体 换行符等格式信息； 最后，再配合 encoding:NSUTF8StringEncoding 编码格式，完成字符串的转换即可

                NSDictionary *finalResponseDict = [questionResponsesDict copy];
                NSError *error = nil;
                NSData *jsonData = [NSJSONSerialization dataWithJSONObject:finalResponseDict options:0 error:&error];

                if (error) {
                    NSLog(@"Error converting dictionary to JSON: %@", error.localizedDescription);
                } else {
                    NSString *jsonString = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];
        //            NSLog(@"%@", jsonString);
				}