從plist中獲取字典對象的問題iphone sdk

Question

用於獲取plist類型爲dictionary的項目的數據類型，即nsmutabledictionary或nsdictionary是什麼？因爲我使用以下代碼從plist中的字典數組中檢索字典對象。

NSMutableDictionary *_myDict = [contentArray objectAtIndex:0]; //APP CRASHES HERE 

NSLog(@"MYDICT : %@",_myDict); 
NSString *myKey = (NSString *)[_myDict valueForKey:@"Contents"] ; 

[[cell lblFeed] setText:[NSString stringWithFormat:@"%@",myKey]]; 

在這裏，第一行顯示了objc_msgsend。 ContentArray是一個nsarray，它的內容顯示了plist中的2個對象。在plist中，它們是字典對象。那爲什麼這個錯誤呢？

編輯：

基本上，我在控制檯contentArray的內容如下所示：

CONTENT ARRAY : 
(
    { 
    favourites = 0; 
    id = 0; 
    story = "This is my first record"; 
    timestamp = 324567; 
}, 
    { 
    favourites = 0; 
    id = 1; 
    story = "This is my second record"; 
    timestamp = 321456; 
} 
) 

我想要從內容數組這些字典對象。

任何人都可以請幫忙嗎？

這真的很緊急。

Thanx提前。

Answer 1

NSDictionary。你不能簡單地說

NSMutableDictionary *_myDict = [contentArray objectAtIndex:0]; 

並希望，這是一個可變的字典現在。這仍然是一種不可改變的正常情節。所以，你應該寫這樣的東西：

NSMutableDictionary *_myDict = [NSMutableDictionary dictionaryWithDictionary:[contentArray objectAtIndex:0]]; 

這將創建一個在plist中的可變字典。

您可以在 「屬性列表編程指南」 中閱讀它，http://developer.apple.com/mac/library/DOCUMENTATION/Cocoa/Conceptual/PropertyLists/index.html

更新：

而且你有一個奇怪的plist內容。可用的XML-的plist類型都提到： http://developer.apple.com/mac/library/DOCUMENTATION/Cocoa/Conceptual/PropertyLists/AboutPropertyLists/AboutPropertyLists.html#//apple_ref/doc/uid/10000048i-CH3-SW1

和整體XML的plist中的結構描述如下： http://developer.apple.com/mac/library/DOCUMENTATION/Cocoa/Conceptual/PropertyLists/UnderstandXMLPlist/UnderstandXMLPlist.html#//apple_ref/doc/uid/10000048i-CH6-SW1

工作的一段代碼

void test() { 
    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; 

    NSMutableArray *arrayIWillWrite = [NSMutableArray array]; 
    NSMutableDictionary *dictionary; 

    dictionary = [NSMutableDictionary dictionary]; 
    [dictionary setObject:[NSNumber numberWithInt:0] forKey:@"favourites"]; 
    [dictionary setObject:[NSNumber numberWithInt:0] forKey:@"id"]; 
    [dictionary setObject:@"This is my first record" forKey:@"story"]; 
    [dictionary setObject:[NSNumber numberWithInt:324567] forKey:@"timestamp"]; 
    [arrayIWillWrite addObject:dictionary]; 

    dictionary = [NSMutableDictionary dictionary]; 
    [dictionary setObject:[NSNumber numberWithInt:0] forKey:@"favourites"]; 
    [dictionary setObject:[NSNumber numberWithInt:1] forKey:@"id"]; 
    [dictionary setObject:@"This is my second record" forKey:@"story"]; 
    [dictionary setObject:[NSNumber numberWithInt:321456] forKey:@"timestamp"]; 
    [arrayIWillWrite addObject:dictionary]; 

    [arrayIWillWrite writeToFile:@"/Users/alex/test.plist" atomically:NO]; 

    NSArray *arrayThatWasRead = [NSArray arrayWithContentsOfFile:@"/Users/alex/test.plist"]; 
    NSLog(@"%@", arrayThatWasRead); 

    NSDictionary *dictionaryFromArrayThatWasRead = [arrayThatWasRead objectAtIndex:0]; 
    NSLog(@"%@", dictionaryFromArrayThatWasRead); 

    [pool release]; 
}