Question

我正在使用DetailViewController创建一个简单的iPad应用程序。一切都很好，但是当我尝试使用多级JSON时，它不再适用于应用程序崩溃。

我检索并循环数据：

-(void) retrieveData{

    NSURL * url = [NSURL URLWithString:getDataURL];
    NSData * data = [NSData dataWithContentsOfURL:url];

    jsonArray = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:nil];

    fruitArray = [[NSMutableArray alloc] init];

    //loop through jsonarray
    for(int i =0;i < jsonArray.count;i++){

        NSString * cName = [[jsonArray objectAtIndex:i] valueForKey:@"cityName"];
        NSString * cFruit = [[jsonArray objectAtIndex:i] valueForKey:@"fruit"];

        //add object to fruitArray array
        [fruitArray addObject:[[Fruits alloc]initWithCityDocumentName:cName andFruit:cFruit]];

    }
    //reload table view
    [self.tableView reloadData];
}

使用json：

[{
    "id": "1",
    "cityName": "London",
    "fruit":"Apple"
}, {
    "id": "2",
    "cityName": "Berlin",
    "fruit":"Pear"
}]

然后我设置了标签（我将它们从故事板/ NIB中挂起）：

- (void)setLabels{
    cityNameLabel.text = currentCity.documentName;
    fruitLabel.text = currentCity.documentFruit;
}

以上所有这些都很好。

但是只要我在JSON中为水果创建多个值，它就不起作用！新JSON：

[{
    "id": "1",
    "cityName": "London",
    "fruit":
        ["Apple", "Pear", "Orange", "Lemon"]
}, {
    "id": "2",
    "cityName": "Berlin",
    "fruit":
        ["Mango", "Melon", "Tomatoe", "Avocado"]
}]

在我看来，我需要以某种方式以编程方式创建标签并在其上循环？基本上，我需要在详细视图控制器中看到每个id的多个值我该怎么办？

我真的需要一个帮助:( 谢谢。

编辑：我现在能够创建一个数组而不是字符串但是当我从它们创建按钮时，它不会让我根据数组中的内容添加标题：

NSMutableArray * cFruit = [[jsonArray objectAtIndex:i] valueForKey:@"fruit"];

然后：

- (void)setLabels{


        for(int i=0;i<=currentCity.documentFruit.count;i++){

        UIButton *button = [UIButton buttonWithType:UIButtonTypeRoundedRect];

        [button addTarget:self
                   action:@selector(setLabels)
         forControlEvents:UIControlEventTouchUpInside];
        //below is my error - looks like it doesn't like setting the titles from array
        [button setTitle:[currentCity.documentFruit objectAtIndex:i] forState:UIControlStateNormal];

        button.frame = CGRectMake(20.0, ButtonHeightPlusOffsetBetweenButtons * i , 280.0, 40.0);

        //Set Tag for future identification
        [button setTag:i];

        [self.view addSubview:button];

    }
    }

Answer 1

fruitArray数组是方法中的局部变量。它从不存储在任何地方。无论你投入什么，它都不会有任何影响。

顺便说一句。

使用for循环（如jsonArray中的NSDictionary * dict），避免每次都进行慢速索引操作。

假设关键水果包含一个字符串，当它包含一个数组时。这迟早会使你的程序崩溃。

不要使用valueForKey，请使用objectForKey。最终，您将通过valueForKey获得非常令人惊讶的结果。

Answer 2

更新JSON之后，您不会收到NSString对象，而是收到NSArray：

NSString * cFruit = [[jsonArray objectAtIndex:i] valueForKey:@"fruit"];

所以你需要做这样的事情：

NSArray *fruitsArray  = [[jsonArray objectAtIndex:i] valueForKey:@"fruit"];
NSString *cFruit = [fruitsArray componentsJoinedByString:@","];

Answer 3

我在这里为您提供完整的代码

#import "ViewController.h"
#import "FruitsBO.h"

@interface ViewController ()

@property (strong, nonatomic) IBOutlet UITableView *tblFruit;
@property (nonatomic, strong) NSMutableArray *arrFruitData;
@end

@implementation ViewController
@synthesize arrFruitData;

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.

    arrFruitData = [[NSMutableArray alloc] init];
    [self loadLocalJson];
}


-(void)loadLocalJson
{
    NSString *pathStringToLocalFile = [[NSBundle mainBundle] pathForResource:@"Fruit" ofType:@"json"];

    NSError *deserializingError;
    NSURL *localFileURL = [NSURL fileURLWithPath:pathStringToLocalFile];
    NSData *contentOfLocalFile = [NSData dataWithContentsOfURL:localFileURL];
    NSArray *objects = [NSJSONSerialization JSONObjectWithData:contentOfLocalFile
                                                options:NSJSONReadingAllowFragments
                                                  error:&deserializingError];

    [self parseFruit:objects];
}


-(void)parseFruit:(NSArray *)arrFruits
{

    for (NSDictionary *dictTemp in arrFruits) {
        FruitsBO *fruit = [[FruitsBO alloc] init];

        fruit.fruitID = [dictTemp objectForKey:@"id"];
        fruit.cityName = [dictTemp objectForKey:@"cityName"];
        fruit.arrFruit = [dictTemp objectForKey:@"fruit"];

        [arrFruitData addObject:fruit];
        fruit = nil;
    }

    [self.tblFruit reloadData];
}

#pragma mark - TableView Delegate -
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
    return [self.arrFruitData count];
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    FruitsBO *obj = [self.arrFruitData objectAtIndex:section];
    return [obj.arrFruit count];
}

-(CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
    return 50;
}

- (CGFloat)tableView:(UITableView *)tableView heightForHeaderInSection:(NSInteger)section
{
    return 30;
}

- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section
{
    FruitsBO *obj = [self.arrFruitData objectAtIndex:section];
    return obj.cityName;
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *simpleTableIdentifier = @"fruitIdentifier";

    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:simpleTableIdentifier];

    if (cell == nil) {
        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:simpleTableIdentifier];
    }

    FruitsBO *objTemp = [self.arrFruitData objectAtIndex:indexPath.section];

    cell.textLabel.text = [objTemp.arrFruit objectAtIndex:indexPath.row];

    return cell;
}

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    [tableView deselectRowAtIndexPath:indexPath animated:YES];
}


- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

@end

这是我的Json

 [{
  "id": "1",
  "cityName": "London",
  "fruit":
  ["Apple", "Pear", "Orange", "Lemon"]
  }, {
  "id": "2",
  "cityName": "Berlin",
  "fruit":
  ["Mango", "Melon", "Tomatoe", "Avocado"]
  },{
  "id": "2",
  "cityName": "Austin",
  "fruit":
  ["Mango"]
  }]

这是我的输出

Output

iOS - DetailViewController不显示来自JSON的多个条目/值

3 个答案: