ios - 为数组创建循环以从 json 字符串获取字符串？

Question

我需要显示一个 TableView ，其中包含来自 Web 服务响应的信息，我没有在此处做错我的示例代码

    NSData *data = [soapResultsString dataUsingEncoding:NSUTF8StringEncoding];
    NSDictionary *json = [NSJSONSerialization JSONObjectWithData:data options:0 error:nil];

    NSArray *array = [json allValues];

    for (int i=0; i<array.count; i++)
    {
        recordResults =NO;
        appDelegate.rateString  =[[[json valueForKey:@"plan_history"]valueForKey:@"rate"]objectAtIndex:i];
        appDelegate.descriptionString=[[[json valueForKey:@"plan_history"]valueForKey:@"description"]objectAtIndex:i];
        appDelegate.validityString=[[[json valueForKey:@"plan_history"]valueForKey:@"validity"]objectAtIndex:i];
        appDelegate.plantypeString=[[[json valueForKey:@"plan_history"]valueForKey:@"plantype"]objectAtIndex:i];

    }

我需要解析 plan_history 中的 4 个值，例如“rate”、“description”、“validity”、“plan type”当我运行我的应用程序时，我在 TableView 中只得到一组值。即我的 json 字符串包含超过 20 条记录，包含费率、描述、有效性和计划类型
你能告诉我如何循环我的 json 值并在 TableView 中显示我的所有记录吗

Answer 1

您应该消除对 allValues 和 valueForKey 的调用，因为重复调用这些方法是处理 JSON 解析的非常低效的方法。

在您的一条评论中，您说您的 JSON 看起来像:

{
    "plan_history": [
        {
            "rate": "₹1000",
            "description": "FullTalktimeTopupRs.1000FullTalktime",
            "validity": "Validity: 0\r",
            "plantype": "FullTalkTime"
        },
        {
            "rate": "₹508",
            "description": "FullTalktimeTopupRs.558morethanFullTalktime",
            "validity": "Validity: 2\r",
            "plantype": "FullTalkTime"
        }
    ]
}

(我想知道在给定您的 allValues 引用的此 plan_history 条目之前是否有内容，但除非您另有说明，否则我会假设这是原始 JSON看起来像。)

如果是这样，要解析它你会这样做:

NSMutableArray *results = [NSMutableArray array];

NSError *error;
NSDictionary *json = [NSJSONSerialization JSONObjectWithData:data options:0 error:&error];
NSArray *planHistory = json[@"plan_history"];

for (NSDictionary *planHistoryEntry in planHistory) {
    NSString *rateString  = planHistoryEntry[@"rate"];
    NSString *description = planHistoryEntry[@"description"];
    NSString *validity    = planHistoryEntry[@"validity"];
    NSString *planType    = planHistoryEntry[@"plantype"];

    // now do whatever you want with these four values.

    // for example, I'd generally create a custom object I defined elsewhere for these four values and add to results, e.g.

    [results addObject:[PlanHistoryEntry planHistoryEntryWithRate:rateString
                                                      description:description
                                                         validity:validity
                                                         planType:planType]];
}

// now do something with results, e.g. store it in some property in `appDelegate`, etc.

其中，PlanHistoryEntry 可以这样定义:

@interface PlanHistoryEntry : NSObject

@property (nonatomic, copy) NSString *rateString;
@property (nonatomic, copy) NSString *planDescription;  // note, do not use `description` for property name
@property (nonatomic, copy) NSString *validity;
@property (nonatomic, copy) NSString *planType;

+ (instancetype) planHistoryEntryWithRate:(NSString *)rateString
                          planDescription:(NSString *)planDescription
                                 validity:(NSString *)validity
                                 planType:(NSString *)planType;

@end

@implementation PlanHistoryEntry

+ (instancetype) planHistoryEntryWithRate:(NSString *)rateString
                          planDescription:(NSString *)planDescription
                                 validity:(NSString *)validity
                                 planType:(NSString *)planType
{
    PlanHistoryEntry *entry = [[self alloc] init];
    entry.rateString = rateString;
    entry.planDescription = planDescription;
    entry.validity = validity;
    entry.planType = planType;

    return entry;
}

@end

但我不想让您迷失在这个答案的 Twig 末节中(因为考虑到这个问题的模棱两可性，我可能在一些细节上弄错了)。关键是您不应该使用 allValues 或 valueForKey。如上所示，只需更直接地导航 JSON 结构即可。