从plist中获取字典对象的问题iphone sdk

Question

用于获取plist类型为dictionary的项目的数据类型，即nsmutabledictionary或nsdictionary是什么？因为我使用以下代码从plist中的字典数组中检索字典对象。

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

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

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

在这里，第一行显示了objc_msgsend。 ContentArray是一个nsarray，它的内容显示了plist中的2个对象。在plist中，它们是字典对象。那为什么这个错误呢？

编辑：

基本上，我在控制台contentArray的内容如下所示：

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; 
} 
) 

我想要从内容数组这些字典对象。

任何人都可以请帮忙吗？

这真的很紧急。

Thanx提前。

Answer 1

NSDictionary。你不能简单地说

NSMutableDictionary *_myDict = [contentArray objectAtIndex:0]; 

并希望，这是一个可变的字典现在。这仍然是一种不可改变的正常情节。所以，你应该写这样的东西：

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

这将创建一个在plist中的可变字典。

您可以在 “属性列表编程指南” 中阅读它，http://developer.apple.com/mac/library/DOCUMENTATION/Cocoa/Conceptual/PropertyLists/index.html

更新：

而且你有一个奇怪的plist内容。可用的XML-的plist类型都提到： http://developer.apple.com/mac/library/DOCUMENTATION/Cocoa/Conceptual/PropertyLists/AboutPropertyLists/AboutPropertyLists.html#//apple_ref/doc/uid/10000048i-CH3-SW1

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

工作的一段代码

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]; 
}