Objective c 屏幕截图代码在模拟器中运行良好，但在iOS设备中无法运行

这是我的截图代码，可以保存在库中或发送电子邮件。问题是，它在模拟器中工作得很好，但当我在屏幕上的任何设备上运行此代码时，它只会得到白色图像。我尝试过iOS 5和iOS 6，但都没有成功 我错的原因应该是什么

    NSInteger myDataLength = 320 * 430 * 4;
    GLubyte *buffer1 = (GLubyte *) malloc(myDataLength);
    GLubyte *buffer2 = (GLubyte *) malloc(myDataLength);    

    //Read image memory form OpenGL
    glReadPixels(0, 50, 320, 430, GL_RGBA, GL_UNSIGNED_BYTE, buffer1);

    //Invert result image buffer into secondary buffer
    for(int y = 0; y < 430; y++)    {
        for(int x = 0; x < 320 * 4; x++) {
            buffer2[(429 - y) * 320 * 4 + x] = buffer1[y * 4 * 320 + x];
        }
    }

    //Create bitmap context
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
    CGContextRef destContext = CGBitmapContextCreate(buffer2, 320, 430, 8, 320 * 4, colorSpace, kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big);

    //Get image from context
    CGImageRef resultContext = CGBitmapContextCreateImage(destContext);
    UIImage *resultImg = [UIImage imageWithCGImage: resultContext];
    CGImageRelease(resultContext);

    //Send to mail or Save to PhotoLibrary
    if (sendMail) {
        [self emailImage: resultImg];
    } else {
        UIImageWriteToSavedPhotosAlbum(resultImg, nil, nil, nil);
    }

    //Release allocated memory
//  [resultImg release];
    free(buffer2);
    free(buffer1);
    CGContextRelease(destContext);
    CGColorSpaceRelease(colorSpace);

NSInteger myDataLength=320*430*4；
GLubyte*buffer1=（GLubyte*）malloc（myDataLength）；
GLubyte*buffer2=（GLubyte*）malloc（myDataLength）；
//从OpenGL读取图像存储器
glReadPixels（0、50、320、430、GL_RGBA、GL_无符号字节、buffer1）；
//将结果图像缓冲区反转为次缓冲区
对于（int y=0；y<430；y++）{
对于（int x=0；x<320*4；x++）{
buffer2[（429-y）*320*4+x]=buffer1[y*4*320+x]；
}
}
//创建位图上下文
CGColorSpaceRef colorSpace=CGColorSpaceCreateDeviceRGB（）；
CGContextRef destContext=CGBitmapContextCreate（缓冲区2、320、430、8、320*4，颜色空间，KCGIMAGEAlphaPremultipledLast | kCGBitmapByteOrder32Big）；
//从上下文中获取图像
CGImageRef resultContext=CGBitmapContextCreateImage（destContext）；
UIImage*resultImg=[UIImage imageWithCGImage:resultContext]；
CGImageRelease（resultContext）；
//发送到邮件或保存到照片库
如果（发送邮件）{
[self-emailImage:resultImg]；
}否则{
UIImageWriteToSavedPhotosAlbum（结果，无，无，无）；
}
//释放分配的内存
//[结果]；
免费（2）；
免费（1）；
CGContextRelease（destContext）；
CGCOLORSPACTERELEASE（色彩空间）；

---

我使用的任何类都是模拟器支持的，而不是设备支持的，如果是，那么是哪一个，因为就我搜索而言，我没有发现类似的类。

试试这个，它在设备上非常适合我：

+ (UIImage *)imageFromView:(UIView *)view inRect:(CGRect)rect {
    CGFloat screenScale = [[UIScreen mainScreen] scale];
    if ([view respondsToSelector:@selector(contentSize)]) {
        UIScrollView *scrollView = (UIScrollView *)view;
        UIGraphicsBeginImageContextWithOptions(scrollView.contentSize, NO, screenScale);
    } else {
        UIGraphicsBeginImageContextWithOptions(view.bounds.size, NO, screenScale);
    }
    CGContextRef resizedContext = UIGraphicsGetCurrentContext();
    [view.layer renderInContext:resizedContext];
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    image = [UIImage imageWithCGImage:CGImageCreateWithImageInRect(image.CGImage, CGRectMake(rect.origin.x*screenScale, rect.origin.y*screenScale, rect.size.width*screenScale, rect.size.height*screenScale))];
    UIGraphicsEndImageContext();
    return [image imageScaledToSize:CGSizeMake(rect.size.width, rect.size.height)];
}

- (UIImage *)imageScaledToSize:(CGSize)newSize {
    if ((self.size.width == newSize.width) && (self.size.height == newSize.height)) {
        return self;
    }
    UIGraphicsBeginImageContextWithOptions(newSize, NO, 0.0);
    [self drawInRect:CGRectMake(0, 0, newSize.width, newSize.height)];
    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();    
    UIGraphicsEndImageContext();
    return newImage;
}

---

试试这个，它在设备上非常适合我：

+ (UIImage *)imageFromView:(UIView *)view inRect:(CGRect)rect {
    CGFloat screenScale = [[UIScreen mainScreen] scale];
    if ([view respondsToSelector:@selector(contentSize)]) {
        UIScrollView *scrollView = (UIScrollView *)view;
        UIGraphicsBeginImageContextWithOptions(scrollView.contentSize, NO, screenScale);
    } else {
        UIGraphicsBeginImageContextWithOptions(view.bounds.size, NO, screenScale);
    }
    CGContextRef resizedContext = UIGraphicsGetCurrentContext();
    [view.layer renderInContext:resizedContext];
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    image = [UIImage imageWithCGImage:CGImageCreateWithImageInRect(image.CGImage, CGRectMake(rect.origin.x*screenScale, rect.origin.y*screenScale, rect.size.width*screenScale, rect.size.height*screenScale))];
    UIGraphicsEndImageContext();
    return [image imageScaledToSize:CGSizeMake(rect.size.width, rect.size.height)];
}

- (UIImage *)imageScaledToSize:(CGSize)newSize {
    if ((self.size.width == newSize.width) && (self.size.height == newSize.height)) {
        return self;
    }
    UIGraphicsBeginImageContextWithOptions(newSize, NO, 0.0);
    [self drawInRect:CGRectMake(0, 0, newSize.width, newSize.height)];
    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();    
    UIGraphicsEndImageContext();
    return newImage;
}

---

我发现我上面的代码是完美的，问题不在这里。实际上问题在于

EagleLayer.drawableProperties

我已更改此代码

eaglLayer.drawableProperties = [NSDictionary dictionaryWithObjectsAndKeys:

            [NSNumber numberWithBool:NO],  
                kEAGLDrawablePropertyRetainedBacking, 
                kEAGLColorFormatRGB565, 
                kEAGLDrawablePropertyColorFormat, nil];

对此

eaglLayer.drawableProperties = [NSDictionary dictionaryWithObjectsAndKeys:

                [NSNumber numberWithBool:YES],  
                    kEAGLDrawablePropertyRetainedBacking, 
                    kEAGLColorFormatRGB565, 
                    kEAGLDrawablePropertyColorFormat, nil];

我刚准备好

        kEAGLDrawablePropertyRetainedBacking = YES

感谢上帝，它工作得很好。

---

但是不知道为什么如果有人知道，请告诉我

我发现我上面的代码是完美的，问题不在这里。实际上问题在于

EagleLayer.drawableProperties

我已更改此代码

eaglLayer.drawableProperties = [NSDictionary dictionaryWithObjectsAndKeys:

            [NSNumber numberWithBool:NO],  
                kEAGLDrawablePropertyRetainedBacking, 
                kEAGLColorFormatRGB565, 
                kEAGLDrawablePropertyColorFormat, nil];

对此

eaglLayer.drawableProperties = [NSDictionary dictionaryWithObjectsAndKeys:

                [NSNumber numberWithBool:YES],  
                    kEAGLDrawablePropertyRetainedBacking, 
                    kEAGLColorFormatRGB565, 
                    kEAGLDrawablePropertyColorFormat, nil];

我刚准备好

        kEAGLDrawablePropertyRetainedBacking = YES

感谢上帝，它工作得很好。

---

但是不知道为什么如果有人知道，请让我知道兄弟这不是解决我的问题兄弟这不是解决我的问题