ios - 无法使用 NSDictionary 的内容填充 UITableViewCells

Question

我已将 iOS 应用程序设置为从某些 Parse 云代码接收 JSON。根据我在下图中看到的内容，JSON 由一个名为 matchCenterDictionary 的 NSDictionary 组成，其中包含 3 个名为 Top 3 的 NSArray 对象，其中每个还包含一个带有 4 个键/值对的 NSDictionary。

我想要做的是在 UITableView 中为 matchCenterDictionary 中出现的 Top 3 的每个实例创建一个新部分，并且使用 4 个键/值对信息(标题、价格、imgurl 等)填充每个相应部分的 3 个单元格。

当我运行模拟时，应用程序崩溃并指向:

cell.textLabel.text = [[[_matchCenterDictionary objectForKey:@"Top 3"] objectAtIndex:0] objectForKey:@"Title"];

作为问题区域，这意味着我没有正确引用它。代码、错误消息和屏幕截图如下。

MatchCenterViewController.m:

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

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

@implementation MatchCenterViewController


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


- (void)viewDidLoad
{
    [super viewDidLoad];

    self.matchCenter = [[UITableView alloc] initWithFrame:self.view.bounds style:UITableViewCellStyleSubtitle];
    self.matchCenter.frame = CGRectMake(0,50,320,self.view.frame.size.height-100);
    _matchCenter.dataSource = self;
    _matchCenter.delegate = self;
    [self.view addSubview:self.matchCenter];

    self.matchCenterDictionary = [[NSDictionary alloc] init];
}

- (void)viewDidAppear:(BOOL)animated
{
    self.matchCenterDictionary = [[NSDictionary alloc] init];

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

                                    if (!error) {
                                        self.matchCenterDictionary = [result objectForKey:@"MatchCenter"];
                                        [_matchCenter reloadData];

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


- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
    return _matchCenterDictionary.count;
}

//the part where i setup sections and the deleting of said sections

- (CGFloat)tableView:(UITableView *)tableView heightForHeaderInSection:(NSInteger)section {
    return 21.0f;
}



- (UIView *)tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section {
    UIView *headerView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 320, 21)];
    headerView.backgroundColor = [UIColor lightGrayColor];

//    _searchTerm = [[self.matchCenterArray firstObject] objectForKey:@"Search Term"];

    UILabel *headerLabel = [[UILabel alloc] initWithFrame:CGRectMake(8, 0, 250, 21)];
//    headerLabel.text = [NSString stringWithFormat:@"%@", searchTerm];
//    headerLabel.font = [UIFont boldSystemFontOfSize:[UIFont systemFontSize]];
//    headerLabel.textColor = [UIColor whiteColor];
    headerLabel.backgroundColor = [UIColor lightGrayColor];
    [headerView addSubview:headerLabel];

    UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
    button.tag = section + 1000;
    button.frame = CGRectMake(300, 2, 17, 17);
    [button setImage:[UIImage imageNamed:@"xbutton.png"] forState:UIControlStateNormal];
    [button addTarget:self action:@selector(deleteButtonPressed:) forControlEvents:UIControlEventTouchUpInside];
    [headerView addSubview:button];
    return headerView;
}



- (IBAction)deleteButtonPressed:(UIButton *)sender {
    NSLog(@"Search Term: '%@'", _searchTerm);

    [PFCloud callFunctionInBackground:@"deleteFromMatchCenter"
                       withParameters:@{
                                        @"searchTerm": _searchTerm,
                                       }
                                block:^(NSDictionary *result, NSError *error) {

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




- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
     return 3;
}



- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    // Initialize cell
    static NSString *CellIdentifier = @"Cell";
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
    if (!cell) {
        // if no cell could be dequeued create a new one
        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier];
    }



    // populate dictionary with results

    //NSDictionary *matchCenterDictionary= [_matchCenterArray objectAtIndex:indexPath.row];

    // title of the item
    cell.textLabel.text = [[[_matchCenterDictionary objectForKey:@"Top 3"] objectAtIndex:0] objectForKey:@"Title"];
    cell.textLabel.font = [UIFont boldSystemFontOfSize:12];

    // price of the item
    cell.detailTextLabel.text = [NSString stringWithFormat:@"$%@", [[[_matchCenterDictionary objectForKey:@"Top 3"] objectAtIndex:0] objectForKey:@"Price"]];
    cell.detailTextLabel.textColor = [UIColor colorWithRed:0/255.0f green:127/255.0f blue:31/255.0f alpha:1.0f];

    // image of the item
    NSData *imageData = [NSData dataWithContentsOfURL:[NSURL URLWithString:[[[_matchCenterDictionary objectForKey:@"Top 3"] objectAtIndex:0] objectForKey:@"Image URL"]]];
    [[cell imageView] setImage:[UIImage imageWithData:imageData]];
    //imageView.frame = CGRectMake(45.0,10.0,10,10);

    return cell;
}

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


/*
#pragma mark - 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

错误消息:

*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSArrayM objectForKey:]: unrecognized selector sent to instance 0xaa1a6e0'
*** First throw call stack:
(
    0   CoreFoundation                      0x02a8d1e4 __exceptionPreprocess + 180
    1   libobjc.A.dylib                     0x0264b8e5 objc_exception_throw + 44
    2   CoreFoundation                      0x02b2a243 -[NSObject(NSObject) doesNotRecognizeSelector:] + 275
    3   CoreFoundation                      0x02a7d50b ___forwarding___ + 1019
    4   CoreFoundation                      0x02a7d0ee _CF_forwarding_prep_0 + 14
    5   Parse+Storyboard                    0x00006129 -[MatchCenterViewController tableView:cellForRowAtIndexPath:] + 313
    6   UIKit                               0x0140411f -[UITableView _createPreparedCellForGlobalRow:withIndexPath:] + 412
    7   UIKit                               0x014041f3 -[UITableView _createPreparedCellForGlobalRow:] + 69
    8   UIKit                               0x013e5ece -[UITableView _updateVisibleCellsNow:] + 2428
    9   UIKit                               0x013fa6a5 -[UITableView layoutSubviews] + 213
    10  UIKit                               0x0137a964 -[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 355
    11  libobjc.A.dylib                     0x0265d82b -[NSObject performSelector:withObject:] + 70
    12  QuartzCore                          0x0065045a -[CALayer layoutSublayers] + 148
    13  QuartzCore                          0x00644244 _ZN2CA5Layer16layout_if_neededEPNS_11TransactionE + 380
    14  QuartzCore                          0x006440b0 _ZN2CA5Layer28layout_and_display_if_neededEPNS_11TransactionE + 26
    15  QuartzCore                          0x005aa7fa _ZN2CA7Context18commit_transactionEPNS_11TransactionE + 294
    16  QuartzCore                          0x005abb85 _ZN2CA11Transaction6commitEv + 393
    17  QuartzCore                          0x005ac258 _ZN2CA11Transaction17observer_callbackEP19__CFRunLoopObservermPv + 92
    18  CoreFoundation                      0x02a5536e __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 30
    19  CoreFoundation                      0x02a552bf __CFRunLoopDoObservers + 399
    20  CoreFoundation                      0x02a33254 __CFRunLoopRun + 1076
    21  CoreFoundation                      0x02a329d3 CFRunLoopRunSpecific + 467
    22  CoreFoundation                      0x02a327eb CFRunLoopRunInMode + 123
    23  GraphicsServices                    0x02cea5ee GSEventRunModal + 192
    24  GraphicsServices                    0x02cea42b GSEventRun + 104
    25  UIKit                               0x0130bf9b UIApplicationMain + 1225
    26  Parse+Storyboard                    0x000024ed main + 141
    27  libdyld.dylib                       0x038e66d9 start + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException

JSON 结构:

Answer 1

再看看你的截图。

你有一个数组的字典。

_matchCenterDictionary 应该是一个 NSArray。

改变

cell.textLabel.text = [[[_matchCenterDictionary objectForKey:@"Top 3"]
                                            objectAtIndex:0] objectForKey:@"Title"];

到

cell.textLabel.text = [[[_matchCenterArray  objectAtIndex:0] 
                                      objectForKey:@"Top 3"] objectForKey:@"Title"];

或更短

cell.textLabel.text = _matchCenterArray[0][@"Top 3"][@"Title"];

当 JSON 嵌套过多时，您可以将其分解以使其更清晰

NSDictionary *top3 = _matchCenterArray[0];
NSString *title = top3[@"Title"];
cell.textLabel.text = title;