Question

我正在将这些数据写入plist文件，但每次写入时，它都会替换之前的任何内容。即，当我重新加载页面时，它会覆盖我之前拥有的任何数据。如何使之前的数据保持不变或有人指出我做的不正确？

- (IBAction)buttonClickSave:(id)sender;
{
 pathList=[self getFilePath];

    if(![[NSFileManager defaultManager] fileExistsAtPath:pathList])
    {

        [[NSFileManager defaultManager] copyItemAtPath:[[NSBundle mainBundle] pathForResource:@"adresses" ofType:@"plist" ]toPath:pathList error:nil];
    }
    NSString *Name = @"Names";
    NSString *email = @"email";
    NSString *phone = @"phone";

    NSMutableArray *values = [[NSMutableArray alloc] initWithObjects:Name, email, phone, nil];
    NSMutableArray *keys = [[NSMutableArray alloc] initWithObjects:kTitleKey, kEmail, kPhone, nil];
    NSDictionary *dict = [[NSDictionary alloc] initWithObjects:values forKeys:keys];
    [self.arraysData addObject:dict];

    [self.arraysData writeToFile:pathList atomically:YES];
}

Answer 1

您所要做的就是从plist读取所有数据，然后附加数据并将此数据写入plist

阅读所有数据

NSMutableArray *plistArray = [NSMutableArray arrayWithContentsOfFile:pathList];

附加数据

[plistArray addObject:YOURDATA];

然后像这样编写你的数组

[dict writeToFile:plistpath atomically:YES];

Answer 2

要初始化阵列，请使用现有文件作为源。这将确保您添加的任何条目不会被覆盖，而是对现有数据进行更改。

因此，无论您在初始化arraysData的哪个位置，请使用以下代码：

arraysData = [NSMutableArray arrayWithContentsOfFile: [self getFilePath]];

Answer 3

在插入之前，您将获得plist中的所有数据值。在将数据与您的逻辑或示例进行比较之后，使用一个用于插入带有覆盖的数据

 // get plist paths from root directory

    NSArray *plistPath = NSSearchPathForDirectoriesInDomains (NSDocumentDirectory, NSUserDomainMask, YES);

// get documents path

NSString *documentsPathPlist = [paths objectAtIndex:0];

NSString *plistDirectory = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask, YES) objectAtIndex:0];    // get the path to our plist file
NSLog(plistDirectory);

    NSString *plistPathRoot = [plistDirectory stringByAppendingPathComponent:@"Sample.plist"];

    //This copies objects of plist to array if there is one
    [array addObjectsFromArray:[NSArray arrayWithContentsOfFile:plistPathRoot]];

//If plist has less than 10 items, insert the new data. Don't use lastInsertionIndex. Else, replace one of the items.
if([array count] < 10)
{
     [array addObject:[textName.text]];
}
else
{
//Update the lastInsertionIndex
lastInsertionIndex++;
lastInsertionIndex %= 10; //// array size = 10

[array replaceObjectAtIndex:lastInsertionIndex withObject:[textName.text]];
}

[array writeToFile:plistPath atomically: TRUE];

另：

下面这个链接已经解释了很多关于Plist而没有覆盖的示例项目。

how-to-stop-overwriting-data-ios

将IOS数据保存为plist

3 个答案: