Question

我有一个系统可以将大量图像保存到plist，除了2个主要问题外，它的效果很好。

首先，当它开始进程时，xcode上的内存转到2G！（完成后放下）其次，与NSUserdefaults相比，它需要太长时间（100张图像超过10秒），我告诉它比这慢。

我首先归档数据。

因为拥有如此多的记忆和如此缓慢的储蓄，我做错了什么？

-(void)saveToFileWithData:(NSMutableDictionary*)dic
{
    NSError *error;
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0];
    NSString *path = [documentsDirectory stringByAppendingPathComponent:@"data.plist"];

    NSFileManager *fileManager = [NSFileManager defaultManager];

    if (![fileManager fileExistsAtPath: path])
    {
         NSString *bundle = [[NSBundle mainBundle] pathForResource:@"data" ofType:@"plist"];
        [fileManager copyItemAtPath:bundle toPath: path error:&error];
    }
    NSData *myData = [NSKeyedArchiver archivedDataWithRootObject:dic];
    BOOL sucess=[myData writeToFile:path atomically:YES];
    if(sucess)
        NSLog(@"saved:%lu",(unsigned long)[myData length]);
    else
        NSLog(@"failed:%lu",[myData length]);

     myData=nil;

}

阅读是这样的：

-(NSMutableDictionary*)readFromFile
{
    NSError *error;
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); //1
    NSString *documentsDirectory = [paths objectAtIndex:0]; //2
    NSString *path = [documentsDirectory stringByAppendingPathComponent:@"data.plist"]; //3

    NSFileManager *fileManager = [NSFileManager defaultManager];

    if (![fileManager fileExistsAtPath: path]) //4
    {
        NSString *bundle = [[NSBundle mainBundle] pathForResource:@"data" ofType:@"plist"]; //5
        [fileManager copyItemAtPath:bundle toPath: path error:&error]; //6
    }
    NSMutableDictionary *dic = [[ NSMutableDictionary alloc] init];
    NSData *serialized = [NSData dataWithContentsOfFile:path];


    //check first if file exist, than if it has content(empty file had 42 bytes-and crashes the archiver)
    if ([[NSFileManager defaultManager] fileExistsAtPath:path] && [serialized length]>1000000)
       dic = (NSMutableDictionary*) [NSKeyedUnarchiver unarchiveObjectWithData:serialized];


    serialized=nil;
    return dic;


}

将它们用于：

NSMutableDictionary *dic =   [[NSMutableDictionary alloc] init];
    dic = [self readFromFile];
   //change dic
[self saveToFileWithData:dic];

Answer 1

没有理由将plist从app bundle复制到Documents目录只是为了阅读它。

plist不是一个好的解决方案，在这种情况下它是巨大的将图像单个文件和图像文件名放在plist中。阅读现在的小plist，然后逐个休息图像。单独读取每个文件会占用较少的内存。

但是，你真的想在内存中同时拥有500MB的图像吗？在阅读了图像信息之后，只需根据需要读取图像，或者使用根据使用情况清除图像的缓存。

从plist中保存和读取对象会导致2G的巨大记忆

1 个答案: