逆向iOS SDK -- _UIImageAtPath 的实现(SDK 5.1)

本文深入探讨了iOS中图像缓存的实现机制,详细解释了如何通过多种文件名组合方式来查找不同分辨率的图像资源,并确保缓存的有效性和正确性。

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注释过的反汇编代码:http://pan.baidu.com/share/link?shareid=3491166579&uk=537224442

伪代码(不精确,仅供参考): 

 

NSString* _UICacheNameForImageAtPath(NSString *imageName,NSBundle *bundle);

NSString* ProductSuffix();

UIImage* GetImageAtPath(NSString *imageFilePath,CGFloat scale);

 

NSMutableDictionary *gCacheNameToImageMap =nil;

NSMutableDictionary *gImageToCacheNameMap =nil;

BOOL __prefer2xImages = NO;

 

UIImage *_UIImageAtPath(NSString *imageFileName,NSBundle *mainBundle, BOOL shouldForce1xScale)

{

    // imageFileName = @"Default.png"

    if ([imageFileName length] == 0)

        return nil;

   

    // bundleIdentifier_imageFileName

    NSString *cacheNameOfImage =_UICacheNameForImageAtPath(imageFileName, mainBundle);

    UIImage *resultImage = nil;

    if (gCacheNameToImageMap !=nil)

    {

        resultImage = [gCacheNameToImageMapobjectForKey:cacheNameOfImage];

        if (resultImage != nil)

        {

            if (![resultImage _isCached])

            {

                [resultImage retain];

            }

           

            [resultImage _setCached:YES];

           

            return resultImage;

        }

    }

    else

    {

        gCacheNameToImageMap = [NSMutableDictionarydictionary];

        gImageToCacheNameMap = [NSMutableDictionarydictionary];

    }

   

    BOOL force1xScale = NO;

    if (__prefer2xImages)

    {

        force1xScale = shouldForce1xScale;

    }

   

    NSString *imageExt = [imageFileNamepathExtension];

    if ([imageExt length] == 0)

    {

        imageExt = @"png";

    }

   

    NSString *bundlePath = nil;

    if (mainBundle != nil)

    {

        bundlePath = [mainBundle bundlePath];

    }

   

    NSString *productSuffix = ProductSuffix();// ~iphone, ~ipad

    NSString *imageNameWithoutSuffix = [imageFileNamestringByReplacingOccurrencesOfString:productSuffixwithString:@""];                   

   

    // Default

    NSString *imageNameWithoutSuffixAndExt = [imageNameWithoutSuffixstringByDeletingPathExtension];

    // Default~iphone

    NSString *imageNameWithSuffix = [imageNameWithoutSuffixAndExtstringByAppendingString:productSuffix];

    // Default@1x

    NSString *imageName1x = [imageNameWithoutSuffixAndExtstringByAppendingString:@"@1x"];

    // Default@1x~iphone

    NSString *imageName1xWithSuffix = [imageName1xstringByAppendingString:productSuffix];

    // Default_1only_

    NSString *imageName_1only_ = [imageNameWithoutSuffixAndExtstringByAppendingString:@"_1only_"];

    // Default_1only_~ipnone

    NSString *imageName_1only_WithSuffix = [imageName_1only_stringByAppendingString:productSuffix];

   

    // Default@2x

    NSString *imageName2x = [imageNameWithoutSuffixAndExtstringByAppendingString:@"@2x"];

    // Default@2x~iphone

    NSString *imageName2xWithSuffix = [imageName2xstringByAppendingString:productSuffix];

    // Default_2only_@2x

    NSString *imageName_2only_2x = [imageNameWithoutSuffixAndExtstringByAppendingString:@"_2only_@2x"];

    // Default_2only_@2x~iphone

    NSString *imageName_2only_2xWithSuffix = [imageName_2only_2xstringByAppendingString:productSuffix];

   

    NSString *targetFileName =nil;

    NSString *targetFilePath =nil;

    if (!force1xScale)

    {

        // Default@2x~iphone.png

        targetFileName = [imageName2xWithSuffix stringByAppendingPathExtension:imageExt];

        targetFilePath = [bundlePath stringByAppendingPathComponent:targetFileName];

        resultImage = GetImageAtPath(targetFilePath,2.0f);

       

        // Default_2only_@2x~iphone.png

        if (resultImage == nil)

        {

            targetFileName = [imageName_2only_2xWithSuffix stringByAppendingPathExtension:imageExt];

            targetFilePath = [bundlePath stringByAppendingPathComponent:targetFileName];

            resultImage = GetImageAtPath(targetFilePath,2.0f);

        }

       

        // Default@2x.png

        if (resultImage == nil)

        {

            targetFileName = [imageName2x stringByAppendingPathExtension:imageExt];

            targetFilePath = [bundlePath stringByAppendingPathComponent:targetFileName];

            resultImage = GetImageAtPath(targetFilePath,2.0f);

        }

       

        // Default_2only_@2x.png

        if (resultImage == nil)

        {

            targetFileName = [imageName_2only_2x stringByAppendingPathExtension:imageExt];

            targetFilePath = [bundlePath stringByAppendingPathComponent:targetFileName];

            resultImage = GetImageAtPath(targetFilePath,2.0f);

        }

    }

   

    if (resultImage == nil)

    {

        // Default~iphone.png

        targetFileName = [imageNameWithSuffix stringByAppendingPathExtension:imageExt];

        targetFilePath = [bundlePath stringByAppendingPathComponent:targetFileName];

        resultImage = GetImageAtPath(targetFilePath,1.0f);

       

        // Default.png

        if (resultImage == nil)

        {

            targetFileName = [imageNameWithoutSuffixAndExt stringByAppendingPathExtension:imageExt];

            targetFilePath = [bundlePath stringByAppendingPathComponent:targetFileName];

            resultImage = GetImageAtPath(targetFilePath,1.0f);

        }

       

        // Default@1x~iphone.png

        if (resultImage == nil)

        {

            targetFileName = [imageName1xWithSuffix stringByAppendingPathExtension:imageExt];

            targetFilePath = [bundlePath stringByAppendingPathComponent:targetFileName];

            resultImage = GetImageAtPath(targetFilePath,1.0f);

        }

       

        // Default_1only_~ipnone.png

        if (resultImage == nil)

        {

            targetFileName = [imageName_1only_WithSuffix stringByAppendingPathExtension:imageExt];

            targetFilePath = [bundlePath stringByAppendingPathComponent:targetFileName];

            resultImage = GetImageAtPath(targetFilePath,1.0f);

        }

       

        // Default@1x.png

        if (resultImage == nil)

        {

            targetFileName = [imageName1x stringByAppendingPathExtension:imageExt];

            targetFilePath = [bundlePath stringByAppendingPathComponent:targetFileName];

            resultImage = GetImageAtPath(targetFilePath,1.0f);

        }

       

        // Default_1only.png

        if (resultImage == nil)

        {

            targetFileName = [imageName_1only_ stringByAppendingPathExtension:imageExt];

            targetFilePath = [bundlePath stringByAppendingPathComponent:targetFileName];

            resultImage = GetImageAtPath(targetFilePath,1.0f);

        }

       

        // Default~iphone

        if (resultImage == nil)

        {

            targetFilePath = [bundlePath stringByAppendingPathComponent:imageNameWithSuffix];

            resultImage = GetImageAtPath(targetFilePath,1.0f);

        }

       

        // Default

        if (resultImage == nil)

        {

            targetFilePath = [bundlePath stringByAppendingPathComponent:imageNameWithoutSuffixAndExt];

            resultImage = GetImageAtPath(targetFilePath,1.0f);

        }

    }

   

    if (resultImage == nil)

    {

        if (!force1xScale)

        {

            // Default@2x.png

            targetFilePath = [mainBundle pathForResource:imageName2x ofType:imageExt];

            resultImage = GetImageAtPath(targetFilePath,2.0f);

           

            // Default_2only_@2x.png

            if (resultImage ==nil)

            {

                targetFilePath = [mainBundle pathForResource:imageName_2only_2x ofType:imageExt];

                resultImage = GetImageAtPath(targetFilePath,2.0f);

            }

        }

       

        // Default.png

        if (resultImage == nil)

        {

            targetFilePath = [mainBundle pathForResource:imageNameWithoutSuffixAndExt ofType:imageExt];

            resultImage = GetImageAtPath(targetFilePath,1.0f);

        }

       

        // Default@1x.png

        if (resultImage == nil)

        {

            targetFilePath = [mainBundle pathForResource:imageName1x ofType:imageExt];

            resultImage = GetImageAtPath(targetFilePath,1.0f);

        }

       

        // Default_1only_.png

        if (resultImage == nil)

        {

            targetFilePath = [mainBundle pathForResource:imageName_1only_ ofType:imageExt];

            resultImage = GetImageAtPath(targetFilePath,1.0f);

        }

    }

   

    if (resultImage != nil)

    {

        [gCacheNameToImageMap setValue:resultImage forKey:cacheNameOfImage];

        [gImageToCacheNameMap setValue:cacheNameOfImage forKey:resultImage];

        [resultImage _setNamed:YES];

        [resultImage _setCached:YES];

    }

   

    return resultImage;

}

内容概要:本文介绍了基于Python实现的SSA-GRU(麻雀搜索算法优化门控循环单元)时间序列预测项目。项目旨在通过结合SSA的全局搜索能力和GRU的时序信息处理能力,提升时间序列预测的精度和效率。文中详细描述了项目的背景、目标、挑战及解决方案,涵盖了从数据预处理到模型训练、优化及评估的全流程。SSA用于优化GRU的超参数,如隐藏层单元数、学习率等,以解决传统方法难以捕捉复杂非线性关系的问题。项目还提供了具体的代码示例,包括GRU模型的定义、训练和验证过程,以及SSA的种群初始化、迭代更新策略和适应度评估函数。; 适合人群:具备一定编程基础,特别是对时间序列预测和深度学习有一定了解的研究人员和技术开发者。; 使用场景及目标:①提高时间序列预测的精度和效率,适用于金融市场分析、气象预报、工业设备故障诊断等领域;②解决传统方法难以捕捉复杂非线性关系的问题;③通过自动化参数优化,减少人工干预,提升模型开发效率;④增强模型在不同数据集和未知环境中的泛化能力。; 阅读建议:由于项目涉及深度学习和智能优化算法的结合,建议读者在阅读过程中结合代码示例进行实践,理解SSA和GRU的工作原理及其在时间序列预测中的具体应用。同时,关注数据预处理、模型训练和优化的每个步骤,以确保对整个流程有全面的理解。
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