JSON數據未加載到UITableView中

Question

我有一個可ping ebay並將JSON返回到iOS應用程序的函數。 我想要做的是用返回的JSON填充我的UITableView。 我已經盡最大努力理解了該代碼的工作方式，但是該表在加載時沒有任何數據。 我認為這可能是因為表是在返回JSON之前加載的，盡管不確定如何解決。

MatchCenterViewController.h

#import <UIKit/UIKit.h>
#import <Parse/Parse.h>
#import "AsyncImageView.h"
#import "SearchViewController.h"

@interface MatchCenterViewController : UIViewController <UITableViewDataSource>

@property (nonatomic) IBOutlet NSString *itemSearch;
@property (nonatomic, strong) NSArray *imageURLs;

@property (strong, nonatomic) NSString *matchingCategoryCondition;
@property (strong, nonatomic) NSString *matchingCategoryLocation;
@property (strong, nonatomic) NSNumber *matchingCategoryMaxPrice;
@property (strong, nonatomic) NSNumber *matchingCategoryMinPrice;


@property (strong, nonatomic) NSArray *matchCenterArray;


@end

MatchCenterViewController.m：

#import "MatchCenterViewController.h"
#import <UIKit/UIKit.h>

@interface MatchCenterViewController () <UITableViewDataSource, UITableViewDelegate>
@property (weak, nonatomic) IBOutlet UITableView *matchCenter;
@end

@implementation MatchCenterViewController



- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}

- (void)viewDidLoad
{

    [super viewDidLoad];


    //perform search with criteria just submitted
    [PFCloud callFunctionInBackground:@"MatchCenterTest"
                       withParameters:@{
                                        @"test": @"Hi",
                                        }
                                block:^(NSDictionary *result, NSError *error) {




                                    if (!error) {
                                        self.matchCenterArray = [result objectForKey:@"Top 3"];

                                        NSLog(@"Test Result: '%@'", result);
                                    }
                                }];

    self.matchCenterArray = [[NSArray alloc] init];
}

- (void)viewDidAppear:(BOOL)animated
{


    [PFCloud callFunctionInBackground:@"MatchCenterTest"
                       withParameters:@{
                                        @"test": @"Hi",
                                        }
                                block:^(NSDictionary *result, NSError *error) {

                                    if (!error) {
                                        NSLog(@"Test Result: '%@'", result);
                                    }
                                }];



}

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
    return 1;
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    return [self.matchCenterArray count];
}



- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{


    static NSString *CellIdentifier = @"Cell";

    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];

    NSDictionary *matchCenterDictionary= [self.matchCenterArray objectAtIndex:indexPath.row];

    cell.textLabel.text = [matchCenterDictionary objectForKey:@"Title"];

    if([matchCenterDictionary objectForKey:@"Price"] != NULL)
    {
        cell.detailTextLabel.text = [NSString stringWithFormat:@"$%@",[matchCenterDictionary   objectForKey:@"Price"]];
    }

    return cell;


}


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




/*
#pragma mark - Navigation

// In a storyboard-based application, you will often want to do a little preparation before navigation
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
    // Get the new view controller using [segue destinationViewController].
    // Pass the selected object to the new view controller.
}
*/

@end

JSON返回：

{
    "Top 3" =     (
                {
            "Item 1" =             (
                                {
                    Title = "Apple iPhone 5s (Latest Model) - 16GB - Silver (AT&T) Smartphone";
                },
                                {
                    Price = "400.0";
                },
                                {
                    "Image URL" = "http://thumbs2.ebaystatic.com/m/mewfVG0QbBiu1nZytMuAlZw/140.jpg";
                },
                                {
                    "Item URL" = "http://www.ebay.com/itm/Apple-iPhone-5s-Latest-Model-16GB-Silver-AT-T-Smartphone-/181431570117?pt=Cell_Phones";
                }
            );
        },
                {
            "Item 2" =             (
                                {
                    Title = "Apple iPhone 5c (Latest Model) - 16GB - Pink (Verizon) Smartphone";
                },
                                {
                    Price = "350.0";
                },
                                {
                    "Image URL" = "http://thumbs4.ebaystatic.com/m/mMPAT67KjfCZF9oorbTf3uw/140.jpg";
                },
                                {
                    "Item URL" = "http://www.ebay.com/itm/Apple-iPhone-5c-Latest-Model-16GB-Pink-Verizon-Smartphone-/191204844039?pt=Cell_Phones";
                }
            );
        },
                {
            "Item 3" =             (
                                {
                    Title = "Apple iPhone 5 \U2013 16GB, White, works with Virgin Mobile US \U2013 NEW";
                },
                                {
                    Price = "359.99";
                },
                                {
                    "Image URL" = "http://thumbs3.ebaystatic.com/m/m5x1uj1iSS2fr691tifrvrw/140.jpg";
                },
                                {
                    "Item URL" = "http://www.ebay.com/itm/Apple-iPhone-5-16GB-White-works-Virgin-Mobile-US-NEW-/141227441998?pt=Cell_Phones";
                }
            );
        }
    );
}

Answer 1

加載數據后，在主線程上重新加載表。

在您的完成塊中：

[PFCloud callFunctionInBackground:@"MatchCenterTest"
                   withParameters:@{
                                    @"test": @"Hi",
                                    }
                            block:^(NSDictionary *result, NSError *error) {

                                if (!error) {
                                    dispatch_async(dispatch_get_main_queue(), ^{
                                        self.matchCenterArray = [result objectForKey:@"Top 3"];
                                        [matchCenter reloadData];
                                    });
                                    NSLog(@"Test Result: '%@'", result);
                                }
                            }];

---

Edit1：另外，我建議在一處適應您的協議。 現在，您在頭文件中使用UITableViewDataSource ，然后在實現文件中使用UITableViewDataSource和UITableViewDelegate 。 堅持一個地點的最佳做法。

---

Edit2：重定位行以根據matchCenterArray的建議將matchCenterArray內容設置到主線程調度上

---

Edit3：基於注釋，您可以更改JSON。 上面列出的當前結構相當繁瑣，因此我建議使用以下更為簡潔（且更易於解析）的方法：

    {
    "Top 3" : [
        {
            "Title" : "Apple iPhone 5s (Latest Model) - 16GB - Silver (AT&T) Smartphone",
            "Price" : "400.0",
            "Image URL" : "http://thumbs2.ebaystatic.com/m/mewfVG0QbBiu1nZytMuAlZw/140.jpg",
            "Item URL" : "http://www.ebay.com/itm/Apple-iPhone-5s-Latest-Model-16GB-Silver-AT-T-Smartphone-/181431570117?pt:Cell_Phones"
        },
        {
            "Title" : "Apple iPhone 5c (Latest Model) - 16GB - Pink (Verizon) Smartphone",
            "Price" : "350.0",
            "Image URL" : "http://thumbs4.ebaystatic.com/m/mMPAT67KjfCZF9oorbTf3uw/140.jpg",
            "Item URL" : "http://www.ebay.com/itm/Apple-iPhone-5c-Latest-Model-16GB-Pink-Verizon-Smartphone-/191204844039?pt:Cell_Phones"
        },
        {
            "Title" : "Apple iPhone 5 16GB, White, works with Virgin Mobile US NEW",
            "Price" : "359.99",
            "Image URL" : "http://thumbs3.ebaystatic.com/m/m5x1uj1iSS2fr691tifrvrw/140.jpg",
            "Item URL" : "http://www.ebay.com/itm/Apple-iPhone-5-16GB-White-works-Virgin-Mobile-US-NEW-/141227441998?pt:Cell_Phones"
        }
    ]
}

現在，您可以像這樣訪問您的值：

// In your completion block:
self.matchCenterArray = [result objectForKey:@"Top 3"];

...
[[self.matchCenterArray objectAtIndex:0] objectForKey:@"Title"] // title of the first object
[[self.matchCenterArray objectAtIndex:2] objectForKey:@"Image URL"] // image URL of the last item

Answer 2

當您從雲中接收數據時，只需將表視圖重新加載到塊中即可。

- (void)viewDidLoad
{

[super viewDidLoad];

self.matchCenterArray = [[NSArray alloc] init];
//perform search with criteria just submitted
[PFCloud callFunctionInBackground:@"MatchCenterTest"
                   withParameters:@{
                                    @"test": @"Hi",
                                    }
                            block:^(NSDictionary *result, NSError *error) {




                                if (!error) {
                                    self.matchCenterArray = [result objectForKey:@"Top 3"];
[yourTableView reloadData];
                                    NSLog(@"Test Result: '%@'", result);
                                }
                            }];


}

還應在.h文件中包括UITableViewDelagete。 並在塊之前初始化數組。