数组为零（即使在 addObject 时也是如此：）

Question

可能的重复：
addObject：数组不起作用（数组仍然为零） < /p>

一切更新

此应用程序是带有选项卡栏控制器的表格视图。我正在记录数组的计数： arrayOfFavourites ，即使我添加一个对象仍然具有 nil 值，我的相关代码，显示的所有对象都在代码中分配和初始化（以前的或现在的），有些是实例，有些是属性：

ListViewController.m：

-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    NSLog(@"TOUCHED CELL!");

    // Push the web view controller onto the navigation stack - this implicitly 
    // creates the web view controller's view the first time through
    [[self navigationController] pushViewController:webViewController animated:YES];

    // Grab the selected item
    entry = [[channel items] objectAtIndex:[indexPath row]];

    if (!entry) {
        NSLog(@"!entry");
    }

    // Construct a URL with the link string of the item
    NSURL *url = [NSURL URLWithString:[entry link]];

    // Construct a request object with that URL
    NSURLRequest *req = [NSURLRequest requestWithURL:url];

    // Load the request into the web view 
    [[webViewController webView] loadRequest:req];

    // Take the cell we pressed
    // IMPORTANT PART
    CELL = [tableView cellForRowAtIndexPath:indexPath];

    [webViewController setItem:entry];

    webViewController = nil;
    webViewController = [[WebViewController alloc] init];
    [entry release];
}

WebViewController.m：

摇动以收藏某个单元格

-(void)motionBegan:(UIEventSubtype)motion withEvent:(UIEvent *)event 
{
    cellToPassOn = nil;

    NSLog(@"Favouriting"); // YES I KNOW SPELLING

    // This is pretty simple, what we do is we take the cell we touched and take its title  and link 
    // then put it inside an array in the Favourites class

    Favourites *fav = [[Favourites alloc] init];
    ListViewController *list = [[ListViewController alloc] init];
    [self setCellToPassOn: [list CELL]];

    if (!item) {
        NSLog(@"NILLED ITEM");
    }

    [[fav arrayOfFavourites] addObject:[item autorelease]];
    [fav setCell: cellToPassOn];
}

Favourites.m：

-(NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    NSLog(@"ROWS NO.");
    NSLog(@"%i", [arrayOfFavourites count]);

    return [arrayOfFavourites count];
}

收藏夹：

一类，在选项卡栏控制器上

WEBVIEWCONROLLER：

不同 Web 视图的控制器

LISTVIEWCONTROLLER：

数据提供者

实际上，当我摇动、重新加载表视图数据并将一个对象添加到数组（收藏夹数组）时，会发生什么情况，计数是一......好！但是当我再次摇晃时（在另一篇文章中，当我按下不同的单元格时，我的应用程序有不同的 webViews。）它仍然是 1...奇怪...如果我转到收藏夹类，该数组仍然是 1.. 好吧。 ..如您所见，我将 arrayOfFavourites 计数返回到 numberOfRowsInSection （即 1），但没有出现任何单元格，并且从未调用 cellForRowAtIndexPath （使用 NSLOG）为什么会发生这种情况我非常生气了！

Answer 1

在您的 Favourites.m numberOfRowsInSection 函数中，看起来您应该这样做：

if(arrayOfFavourites == NULL)
{
    arrayOfFavourites = [[NSMutableArray alloc] init];
}

因为您在每次调用 numberOfRowsInSection 时都重新初始化（并且可能泄漏）（每次调用都会调用该函数）表需要知道必须显示多少行的时间——即经常）。

Answer 2

每次执行 -motionBegan:withEvent: 时都会创建和销毁一个新的收藏夹对象，并且每次执行 -tableView:numberOfRowsInSection: 时都会创建一个新数组。如果您希望数据在这些事件之外持续存在，则需要保留对象。

Answer 3

让我们回顾一下您的代码的这一部分：

-(void)motionBegan:(UIEventSubtype)motion withEvent:(UIEvent *)event {

cellToPassOn = nil;
NSLog(@"Favouriting"); // YES I KNOW SPELLING

// This is pretty simple, what we do is we take the cell we touched and take its title  and link 
// then put it inside an array in the Favourites class

// HERE you are creating a NEW fav
Favourites *fav = [[Favourites alloc] init];
// HERE you are creating a NEW list
ListViewController *list = [[ListViewController alloc] init];
//  SO HERE what is "CELL" doing, returning some constant or static object?
[self setCellToPassOn: [list CELL]];

// HERE what is item and where does it come from
if (!item) {
    NSLog(@"NILLED ITEM");
}

// Here you take an array of an object you just created and autoreleasing the item
// this is not the regular way to handle memory management in Cocoa, 
// depending on what you are doing to item else where you could get item == deallocated pretty soon
[[fav arrayOfFavourites] addObject:[item autorelease]];
[fav setCell: cellToPassOn];

HERE you are releasing fav
[fav release];
HERE fav don't exist anymore as well as the array to which you've added something to it.
[list release];
item = nil;
}

除非我错误地阅读了您的代码，否则我感觉您正在尝试对“易失性”对象进行持久化。

您需要为这些对象创建一个@property，以便在该方法调用中存活更长时间。
每次创建一个新对象时，它都是新的，并且不了解前一个对象。

如果我们看一下这段代码：

-(NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
// HERE everytime the tableview is asking for the numberOfRowsInSection, you create a new array 
// And that new empty array is replacing your old one.  
// That is your "weird" thing, it's doing what you are asking it to do, set it back to a new empty array.
arrayOfFavourites = [[NSMutableArray alloc] init];

NSLog(@"ROWS NO.");
NSLog(@"%i", [arrayOfFavourites count]);

return [arrayOfFavourites count];
}