發佈2次？

Question

我對釋放我首先分配/初始化然後複製的對象感到困惑。據我瞭解內存管理手冊我應該釋放對象2次，因爲通過分配它，然後複製它，我應該保留值2？ 所以第一個版本會降低到一個和第二個0？ 如果我釋放它兩次，我會將消息發送到dealloc對象。如果我一旦在應用程序中沒有出現問題，那麼我就可以做到這一點，但是我對理解對象C mem有一個瞭解。管理:)））

我能想到的唯一解釋是，當你從一個soecific上下文釋放一個對象時，它會立即釋放它，無論保留數的值是多少？

在片斷波紋管XMLELEMENT是混亂的一個....

// LSnippet of code for TouchXML 
for (CXMLElement *resultElement in resultNodes) { 

    NSMutableDictionary *xmlElement = [[NSMutableDictionary alloc] init]; 

    // Create a counter variable as type "int" 
    int counter; 

    // Loop through the children of the current node 
    for(counter = 0; counter < [resultElement childCount]; counter++) { 

     // Add each field to the blogItem Dictionary with the node name as key and node value as the value 
     [xmlElement setObject:[[resultElement childAtIndex:counter] stringValue] forKey:[[resultElement childAtIndex:counter] name]]; 
    } 

    // Add the blogItem to the global blogEntries Array so that the view can access it. 


    [tempReturnedElements addObject:[xmlElement copy]]; 
    [xmlElement release];  
    //[xmlElement release]; but NOT! 


} 

UPDATE：整個方法的代碼：

+(void) runXPath:(NSString *)xPathExpression{ 

CXMLDocument *rssParser = [[[CXMLDocument alloc] initWithXMLString:xmlStringContent options:0 error:nil] autorelease]; 

// Create a new Array object to be used with the looping of the results from the rssParser 
NSArray *resultNodes = NULL; 


// Set the resultNodes Array to contain an object for every instance of an node in our RSS feed 
resultNodes = [rssParser nodesForXPath:xPathExpression error:nil]; 

NSMutableArray *tempReturnedElements = [[NSMutableArray alloc]init]; 

// Loop through the resultNodes to access each items actual data 
for (CXMLElement *resultElement in resultNodes) { 

    // Create a temporary MutableDictionary to store the items fields in, which will eventually end up in blogEntries 
    NSMutableDictionary *xmlElement = [[NSMutableDictionary alloc] init]; 

    // Create a counter variable as type "int" 
    int counter; 

    // Loop through the children of the current node 
    for(counter = 0; counter < [resultElement childCount]; counter++) { 

     // Add each field to the blogItem Dictionary with the node name as key and node value as the value 
     [xmlElement setObject:[[resultElement childAtIndex:counter] stringValue] forKey:[[resultElement childAtIndex:counter] name]]; 
    } 

    // Add the blogItem to the global blogEntries Array so that the view can access it. 


    [tempReturnedElements addObject:[xmlElement copy]]; 
//***** Crushes if I use: 
//***** [tempReturnedElements addObject:[[xmlElement copy] autorelease]]; 
    [xmlElement release]; 



} 


[lotojuegosAppDelegate setMyReturnedXmlElements:[tempReturnedElements copy]]; 

[tempReturnedElements release]; 

}

由於提前， 盧卡

Answer 1

規則很簡單：每個alloc/init，copy或retain必須當你想放棄所有權調用只有一個release或autorelease。您只撥打了一個alloc/init，因此您只能撥打release一次。

這條線：

[tempReturnedElements addObject:[xmlElement copy]]; 

應該寫成：

[tempReturnedElements addObject:[[xmlElement copy] autorelease]]; 

的原因是：copy爲您提供了一個新的對象。 xmlElement指向的對象的保留計數/所有權保持不變，但新對象現在屬於您。你現在負責發佈它。看到這個答案的第一段：你調用了副本，你需要調用釋放所產生的對象。

Answer 2

在[xmlElement copy]中，只有返回的對象（i .E。該副本）需要被釋放。接收者（xmlElement）的所有權（保留計數）不變。

所以，正確的做法應該是

NSDictionary* xmlElemCopy = [xmlElement copy]; 
    [tempReturnedElements addObject:xmlElemCopy]; 
    [xmlElemCopy release]; 
    [xmlElement release];