的NSMutableDictionary，分配，init和reiniting

Question

在下面的代碼：

//anArray is a Array of Dictionary with 5 objs. 

//here we init with the first 
NSMutableDictionary *anMutableDict = [[NSMutableDictionary alloc] initWithDictionary:[anArray objectAtIndex:0]]; 

... use of anMutableDict ... 
//then want to clear the MutableDict and assign the other dicts that was in the array of dicts 

for (int i=1;i<5;i++) { 
    [anMutableDict removeAllObjects]; 
    [anMutableDict initWithDictionary:[anArray objectAtIndex:i]]; 
} 

爲什麼這會崩潰嗎？如何正確的方式來清除無效的字典並分配新的字典？

謝謝你的。

馬科斯。

Answer 1

您不會「重新啓動」對象 - 永遠。初始化意味着在新編寫的實例上使用，並且可能會在初始化完成後做出假設，但這種假設不正確。在NSMutableDictionary的情況下，您可以使用setDictionary:將字典的內容用新字典或addEntriesFromDictionary:完全替換爲從其他字典添加條目（除非存在衝突時不刪除當前條目）。

更一般地說，您可以釋放該字典並在數組中創建字典的mutableCopy。

Answer 2

如果使用自動釋放的字典，你的代碼就會簡單得多：

NSMutableDictionary *anMutableDict = [NSMutableDictionary dictionaryWithDictionary:[anArray objectAtIndex:0]]; 

... use of anMutableDict ... 

for (int i=1; i<5; i++) 
{ 
    anMutableDict = [NSMutableDictionary dictionaryWithDictionary:[anArray objectAtIndex:i]]; 
} 

但我沒有看到環你在年底有點。

Answer 3

這不是你如何使用init/alloc。相反，請嘗試：

//anArray is a Array of Dictionary with 5 objs. 

//here we init with the first 
NSMutableDictionary *anMutableDict = [[NSMutableDictionary alloc] initWithDictionary:[anArray objectAtIndex:0]]; 

... use of anMutableDict ... 
//then want to clear the MutableDict and assign the other dicts that was in the array of dicts 

for (int i=1;i<5;i++) { 
    [anMutableDict removeAllObjects]; 
    [anMutableDict addEntriesFromDictionary:[anArray objectAtIndex:i]]; 
}