UITableView 空白

Question

我以为我在翻滚，然后又趴在脸上。

插入我的代码以将 plist 数据排序到部分后，我的 tableview 显示为空白。 请注意，我已经重新连接了 dataSource 和委托，并且知道 prepareForSegue 是不正确的——一旦我有单元格显示我将更新它（没有部分的工作）。 显然是我，但我看不到错误并且它正在构建良好。

Ps：我知道它没有针对内存管理进行优化。一旦 tableview 工作，我将声明一个 keys 属性并将它们分类，等等。 此外，没有 NSLog 语句的原因是我的 XCODE 不会在控制台中输出任何内容。

谢谢

#import "RCViewController.h"
#import "detailView.h"

@interface RCViewController ()

@end

@implementation RCViewController

@synthesize orderedPlistWords, tableView;
@synthesize alphabeticallySortedWords;

static NSString *CellIdentifier = @"Cell Identifier";

-(NSDictionary *)alphabeticallySortedWords:(NSArray *)wordsArray {
    NSMutableDictionary *buffer = [[NSMutableDictionary alloc]init];

    for (NSDictionary *dict in orderedPlistWords) {
        NSString *word = [dict objectForKey:@"Word"];
        NSString *firstLetter = [[word substringToIndex:1]uppercaseString];

        if ([buffer objectForKey:firstLetter]) {
            [(NSMutableArray *)[buffer objectForKey:firstLetter]addObject:dict];
        }
        else {
            NSMutableArray *mutableArray = [[NSMutableArray alloc]initWithObjects:dict, nil];
            [buffer setObject:mutableArray forKey:firstLetter];
        }
    }
    NSArray *keys = [buffer allKeys];
    for (int j; j<keys.count; j++) {
        NSString *key = [keys objectAtIndex:j];
        [(NSMutableArray *)[buffer objectForKey:key]sortUsingSelector:@selector(localizedCaseInsensitiveCompare:)];
    }
    NSDictionary *result = [NSDictionary dictionaryWithDictionary:buffer];
    return result;

}


-(NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {

    NSArray *keys = [self.alphabeticallySortedWords allKeys];
    return [keys count];
}

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


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




    NSArray *unsortedKeys = [self.alphabeticallySortedWords allKeys];
    NSArray *sortedKeys = [unsortedKeys sortedArrayUsingSelector:@selector(localizedCaseInsensitiveCompare:)];
    NSString *key = [sortedKeys objectAtIndex:[indexPath section]];
    NSArray *wordsForSection = [[self.alphabeticallySortedWords objectForKey:key]objectForKey:@"Word"];
    NSString *word = [wordsForSection objectAtIndex:[indexPath row]];

    [cell.textLabel setText:word];

    return cell;

}

-(NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {

    NSArray *unsortedKeys = [self.alphabeticallySortedWords allKeys];
    NSArray *sortedKeys = [unsortedKeys sortedArrayUsingSelector:@selector(localizedCaseInsensitiveCompare:)];
    NSString *key = [sortedKeys objectAtIndex:section];
    NSArray *wordsForSection = [[self.alphabeticallySortedWords objectForKey:key]objectForKey:@"Word"];
    return  [wordsForSection count];
}

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {


    UITableViewCell *cell = [tableView cellForRowAtIndexPath:indexPath];
    [self performSegueWithIdentifier:@"showDetail" sender:cell];
}


-(NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section {
    NSArray *keys = [[self.alphabeticallySortedWords allKeys]sortedArrayUsingSelector:@selector(localizedCaseInsensitiveCompare:)];
    NSString *key = [keys objectAtIndex:section];
    return key;
}


-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender{
    if ([segue.identifier isEqualToString:@"showDetail"]) {
        NSIndexPath *indexPath = [self.tableView indexPathForSelectedRow];
        detailView *destViewController = segue.destinationViewController;

        destViewController.word = [[self.orderedPlistWords objectAtIndex:indexPath.row]valueForKey:@"Word"];
        destViewController.definition = [[self.orderedPlistWords objectAtIndex:indexPath.row]valueForKey:@"Definition"];
    }
}



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

    NSString *plistPath = [[NSBundle mainBundle]pathForResource:@"words" ofType:@"plist"];
    NSSortDescriptor *descriptor = [NSSortDescriptor sortDescriptorWithKey:@"Word" ascending:YES selector:@selector(caseInsensitiveCompare:)];


    NSMutableArray *plistWords = [[NSMutableArray alloc]initWithContentsOfFile:plistPath];
    self.orderedPlistWords = [plistWords sortedArrayUsingDescriptors:[NSArray arrayWithObject:descriptor]];

    [self.tableView registerClass:[UITableViewCell class] forCellReuseIdentifier:CellIdentifier];

}

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

@end

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<array>
    <dict>
        <key>Word</key>
        <string>Pitch</string>
        <key>Definition</key>
        <string>Ground players play on</string>
    </dict>
    <dict>
        <key>Word</key>
        <string>Goal</string>
        <key>Definition</key>
        <string>Point awarded when ball crosses goal line</string>
    </dict>
    <dict>
        <key>Word</key>
        <string>Yellow Card</string>
        <key>Definition</key>
        <string>Penalise player for foul</string>
    </dict>
</array>
</plist>

Answer 1

你有一个属性，alphabeticallySortedWords，你的 UITableViewDataSource 方法引用了它，但你从不填充。您有一个类似名称的方法，alphabeticallySortedWords，但它需要一个数组参数。

每当您遇到此类问题时。在numberOfRowsInSection 和numberOfSectionsInTableView 中放置断点。这将确认这些方法完全被调用（即确保您的场景的基类设置正确，确保您已设置表格视图属性的数据源等）。在这种情况下，如果您这样做了，您会立即发现 alphabeticallySortedWords 是 nil。

---

顺便说一句，这里也有其他错误：

在numberOfRowsInSection 中，有一行内容是：

NSArray *wordsForSection = [[self.alphabeticallySortedWords objectForKey:key] objectForKey:@"Word"];

应该是：

NSArray *wordsForSection = [self.alphabeticallySortedWords objectForKey:key];

同样，在cellForRowAtIndexPath 中，您有几行说：

NSArray *wordsForSection = [[self.alphabeticallySortedWords objectForKey:key] objectForKey:@"Word"];
NSString *word = [wordsForSection objectAtIndex:[indexPath row]];

他们应该是：

NSArray *wordsForSection = [self.alphabeticallySortedWords objectForKey:key];
NSString *word = [[wordsForSection objectAtIndex:[indexPath row]] objectForKey:@"Word"];

在这两种情况下，您都在错误的时间提取了Word。