截断的核心数据对象

我正在NSData*对象中保存双精度数组,该对象在核心数据(SQLite)数据模型中作为二进制属性持久化。我这样做是为了在iPhone应用程序中存储用于绘图的采样数据。有时,当二进制对象中有300多个双精度对象时,并不是所有的双精度对象都被保存到磁盘上。当我退出并重新启动我的应用程序时,可能会有多达25个数据点被保留,或者多达300个。

鉴于使用synchronous=FULL会导致性能问题的警告,我正在寻求建议和建议。

谢谢

]]

从Data.m

@dynamic dataSet; // NSData * attribute of Data entity

 - (void) addDatum:(double_t)datum
    {
    DLog(@"-[Data addDatum:%f]", datum);
    [self addToCache:datum];
    }

- (void) addToCache:(double_t)datum
    {
    if (cache == nil)
        {
        cache = [NSMutableData dataWithData:[self dataSet]];
        [cache retain];
        }
    [cache appendBytes:&datum length:sizeof(double_t)];
    DLog(@"-[Data addToCache:%f] ... [cache length] = %d; cache = %p", datum, [cache length], cache);
    [self flushCache];
    }

- (void) wrapup
    {
    DLog(@"-[Data wrapup]");
    [self flushCache];
    [cache release];
    cache = nil;
    DLog(@"[self isFault] = %@", [self isFault] ? @"YES" : @"NO"); // [self isFault] is always NO.
    }

- (void) flushCache
    {
    DLog(@"flushing cache to store");
    [self setDataSet:cache];
    DLog(@"-[Data flushCache:] [[self dataSet] length] = %d", [[self dataSet] length]);
    }

- (double*) bytes
    {
    return (double*)[[self dataSet] bytes];
    }

- (NSInteger) count
    {
    return [[self dataSet] length]/sizeof(double);
    }

- (void) dump
    {
    ALog(@"Dump Data");
    NSInteger numDataPoints = [self count];
    double *data = (double*)[self bytes];
    ALog(@"numDataPoints = %d", numDataPoints);
    for (int i = 0; i