如何将新项目附加到plist?

使用cocoa,您需要将文件读取到内存中,附加新的dictionary对象,然后将其写回文件系统。如果您使用一个XML plist,您可以很容易地解析它并增量地写入文件,但它也会大一点,因此它不太可能值得。

如果重写plist花费的时间太长,则应使用数据库(可能通过核心数据)进行调查。除非文件很大,我怀疑这将是一个问题,即使iPhone的内存容量和闪存写入速度。

(我为那些不想点击类似问题链接的人复制了这个,我在这里回答了: A question on how to Get data from plist & how should it be layout )

以下是使用nsdictionary从plist读取和写入值的两种方法:

- (NSMutableDictionary*)dictionaryFromPlist {
    NSString *filePath = @"myPlist.plist";
    NSMutableDictionary* propertyListValues = [[NSMutableDictionary alloc] initWithContentsOfFile:filePath];
    return [propertyListValues autorelease];
}

- (BOOL)writeDictionaryToPlist:(NSDictionary*)plistDict{
    NSString *filePath = @"myPlist.plist";
    BOOL result = [plistDict writeToFile:filePath atomically:YES];
    return result;
}

然后在代码块的某个地方:

// Read key from plist dictionary
NSDictionary *dict = [self dictionaryFromPlist];
NSString *valueToPrint = [dict objectForKey:@"Executable file"];
NSLog(@"valueToPrint: %@", valueToPrint);

// Write key to plist dictionary
NSString *key = @"Icon File";
NSString *value = @"appIcon.png";
[dict setValue:value forKey:key];

// Write new plist to file using dictionary
[self writeDictionaryToPlist:dict];

这就是我将数据添加到plist的方式:

    NSString *filePath = [self dataFilePath];
if ([[NSFileManager defaultManager] fileExistsAtPath:filePath]) 
{
    NSMutableArray *array = [[NSMutableArray alloc] initWithContentsOfFile:filePath];
    [array addObject:countdownLabel.text];
    [array writeToFile:[self dataFilePath] atomically:YES];
    [array release];
}
else
{
    NSArray *array = [NSArray arrayWithObject:countdownLabel.text];
    [array writeToFile:filePath atomically:YES];
}