使用远程.plist覆盖本地.plist文件

Question

我的应用程序在启动时加载一个本地list.plist文件。

然后它有一个从我的网站获取.plist文件的远程版本的refreshTable按钮。

App Launch
    local list.plist loads
       user hits refreshList button
          local list.plist is overwritten by remote list.plist
             local list.plist updated until remote list.plist updates again

初始化数据的方法：

    //Remote data 
    list = [[NSMutableArray alloc] initWithContentsOfURL:[NSURL URLWithString:@"http://mywebsite.com/list.plist"]];
    NSSortDescriptor *descriptor = [[[NSSortDescriptor alloc] initWithKey:@"name" ascending:YES selector:@selector(localizedCaseInsensitiveCompare:)] autorelease];
    sortedList = [[list sortedArrayUsingDescriptors:[NSArray arrayWithObject:descriptor]] retain];

    //Local data
    NSString *localPath = [[NSBundle mainBundle] pathForResource:@"list" ofType:@"plist"];
   localList = [[NSMutableArray alloc] initWithContentsOfFile:localPath];
    NSSortDescriptor *localDescriptor = [[[NSSortDescriptor alloc] initWithKey:@"name" ascending:YES selector:@selector(localizedCaseInsensitiveCompare:)] autorelease];
    localSortedList = [[localList sortedArrayUsingDescriptors:[NSArray arrayWithObject:localDescriptor]] retain];

这是刷新的方法：

- (void) refreshTable:(id)sender

{  
   //Remote .plist 
   list = [[NSMutableArray alloc] initWithContentsOfURL:[NSURL URLWithString:@"http://mywebsite.com/list.plist"]];
    NSSortDescriptor *descriptor = [[[NSSortDescriptor alloc] initWithKey:@"name" ascending:YES selector:@selector(localizedCaseInsensitiveCompare:)] autorelease];
   sortedList = [[list sortedArrayUsingDescriptors:[NSArray arrayWithObject:descriptor]] retain];
    [self.tableView reloadData];
    //now write remote plist to local plist
}

下载完远程plist后，如何重写本地plist？

我正在考虑清空包含本地plist的本地数组，并用远程数组填充它，我是这样做的：

我以我认为的方式解决了问题：

 //Remote .plist 
    list = [[NSMutableArray alloc] initWithContentsOfURL:[NSURL URLWithString:@"http://phillipapps.com/mntlion/list.plist"]];
    NSSortDescriptor *descriptor = [[[NSSortDescriptor alloc] initWithKey:@"name" ascending:YES selector:@selector(localizedCaseInsensitiveCompare:)] autorelease];
    sortedList = [[list sortedArrayUsingDescriptors:[NSArray arrayWithObject:descriptor]] retain];

    NSLog(@"list: %@",list);
    [localList removeAllObjects];
    [localList addObjectsFromArray:list];
    localSortedList = [[localList sortedArrayUsingDescriptors:[NSArray arrayWithObject:descriptor]] retain];
    NSLog(@"locallist: %@",localList);
    [self.tableView reloadData];

它可以工作，但是我如何用list的内容重写localList

Answer 1

所以…经过几个小时的闲聊，我们把问题解决了。

- (NSArray*)readPlist
{
    NSArray *documentPaths = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES);
    NSString *plistPath = [[documentPaths lastObject] stringByAppendingPathComponent:@"localFile.plist"];

    NSFileManager *fMgr = [NSFileManager defaultManager];
    if (![fMgr fileExistsAtPath:plistPath]) {
        plistPath = [[NSBundle mainBundle] pathForResource:@"template" ofType:@"plist"];
    }
    return [NSArray arrayWithContentsOfFile:plistPath];
}

- (void)writePlist:(NSArray*)arr
{
    NSArray *documentPaths = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES);
    NSString *plistPath = [[documentPaths lastObject] stringByAppendingPathComponent:@"localFile.plist"];

    NSFileManager *fMgr = [NSFileManager defaultManager];
    if (![fMgr fileExistsAtPath:plistPath])
        [fMgr removeItemAtPath:plistPath error:nil];

    [arr writeToFile:plistPath atomically:YES];
}

初始化ivar：

self.plistArray = [self readPlist];

从服务器加载新的plist后，您必须调用以下代码：

self.plistArray = [NSArray arrayWithContentsOfURL:[NSURL URLWithString:@"http://mywebsite.com/list.plist"]];
[self writePlist:plistArray]; // e.g. for caching
[self.tableView reloadData];

Answer 2

我做的几乎就是你在我的应用程序中要做的事情。您不能写入NSBundle，因此步骤如下所示：

1. 尝试从缓存目录加载plist，如果成功，请转到3.
2. 从捆绑包加载plist
3. 检查加载的plist是否为最新(或者，通过按下新的plist
4. 触发进一步的步骤保存到缓存目录

代码看起来像这样：

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES);
NSString *cache = [paths objectAtIndex:0];

ratios = [NSDictionary dictionaryWithContentsOfFile:[cache stringByAppendingPathComponent:@"devices.plist"]];
if (ratios == nil) {
    ratios = [NSDictionary dictionaryWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@"devices" ofType:@"plist"]];
}

NSString *device = [[UIDevice currentDevice] machine];
NSDictionary *d = [ratios objectForKey:device];
if (d!=nil) {
    pixelInchRatio = [[d objectForKey:@"pixelInchRatio"] doubleValue];
    bezelWidth = [[d objectForKey:@"bezelWidth"] doubleValue];
    bezelHeight = [[d objectForKey:@"bezelHeight"] doubleValue];
} else if (fetch) {
    [[[[RulerDimensionDownload alloc] init] autorelease] startDownload];
}

然后在下载器中保存如下所示：

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES);
NSString *cache = [paths objectAtIndex:0];

[[NSFileManager defaultManager] createDirectoryAtPath:cache withIntermediateDirectories:YES attributes:nil error:nil];
[ratios writeToFile:[cache stringByAppendingPathComponent:@"devices.plist"] atomically:YES];

以下是一些解释：

每个示例中的前几行、路径和缓存定义只是获取应用程序的缓存目录的位置。我用它来存储最新的版本我是我的plist。

因此，在加载代码中，我首先尝试从缓存目录加载plist。如果失败(ratios为空)，我就从我的应用程序包(这是我随应用程序附带的plist的版本)中加载它。

在此之后，我检查plist是否具有所需的信息。( plist对每种设备类型都有一个定义。如果设备不在plist中，那么我知道我需要尝试更新plist)

如果plist已过期，我将使用我编写的类RulerDimensionDownload开始下载。下载完成后，我将文件保存到缓存目录中。然后，下一次需要加载plist时，它将首先被加载，而不会再查看已发送的plist。(我还发送了带有新plist的通知)