addObject：数组不起作用（数组仍然为零）

Question

这个应用程序是一个带有标签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：

摇动即可收藏单元格

 -(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];
[fav release];
[list release];
item = nil;

 }

Favourites.m：

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

arrayOfFavourites = [[NSMutableArray alloc] init];


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

return [arrayOfFavourites count];
}

Answer 1

为什么要在 tableview:numberOfRowsInSection 中初始化数组？这将导致每次重新加载表视图时重置数组。这可能是你的问题。

Answer 2

您正在 -(NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section 中分配数组，

尝试将其分配到其他地方。

Answer 3

您可以在 tableView:numberOfRowsInSectionMethod 中分配 arrayOfFavorites，但首先需要检查它是否为 nil。

if( !arrayOfFavorites )
    arrayOfFavoriges = [[NSMutableArray alloc] init];

然后您应该在 dealloc 方法中释放它：[arrayOfFavorites release]。

Answer 4

 -(void)motionBegan:(UIEventSubtype)motion withEvent:(UIEvent *)event {
 cellToPassOn = nil;
 NSLog(@"Favouriting"); // YES I KNOW SPELLING
 // HERE creation of a Brand NEW empty Favourites instance
 Favourites *fav = [[Favourites alloc] init];
 // HERE creation of a Brand NEW empty ListViewController instance
 ListViewController *list = [[ListViewController alloc] init];
 // HERE we hope that the ListViewController as CELL other then nil when it is Brand NEW
 [self setCellToPassOn: [list CELL]];

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

 [[fav arrayOfFavourites] addObject:[item autorelease]];
 [fav setCell: cellToPassOn];
 [fav release];
 // HERE the fav instance get deallocated and don't exist anymore
 [list release];
 // HERE the list instance get deallocated and don't exist anymore
 item = nil;
 }

在此代码中，list和fav仅存在于该方法的主体中，尝试获取它们所保存的值将失败，因为list 和 fav 在该方法之外不存在。