Ios 崩溃“无法执行支持代码以读取 Objective-C”在 ios 12.4.2 上不在 12.0.1

Question

This method returns a qr code image of a string. It works correctly on Ios 12.0.1 (iphone SE) but it crash on 12.4.2 (iphone 6). The method crash when i try to assign the resultant UIImage to an UIImageView , the resultant UIImage is not nil.

-(UIImage*)get_QR_image :(NSString*)qrString :(UIColor*)ForeGroundCol :(UIColor*)BackGroundCol{

    NSData *stringData = [qrString dataUsingEncoding: NSUTF8StringEncoding];

    CIFilter *qrFilter = [CIFilter filterWithName:@"CIQRCodeGenerator"];
    [qrFilter setValue:stringData forKey:@"inputMessage"];
    [qrFilter setValue:@"H" forKey:@"inputCorrectionLevel"];


    CIImage *qrImage = qrFilter.outputImage;
    float scaleX = 320;
    float scaleY = 320;


    CIColor *iForegroundColor = [CIColor colorWithCGColor:[ForeGroundCol CGColor]];
    CIColor *iBackgroundColor = [CIColor colorWithCGColor:[BackGroundCol CGColor]];

    CIFilter * filterColor = [CIFilter filterWithName:@"CIFalseColor" keysAndValues:@"inputImage", qrImage, @"inputColor0", iForegroundColor, @"inputColor1", iBackgroundColor, nil];

    CIImage *filtered_image = [filterColor valueForKey:@"outputImage"];

    filtered_image = [filtered_image imageByApplyingTransform:CGAffineTransformMakeScale(scaleX, scaleY)];

    UIImage *result_image = [UIImage imageWithCIImage:filtered_image
                                                 scale:[UIScreen mainScreen].scale
                                           orientation:UIImageOrientationUp];


    return result_image;
}

the line involved in crash is:

filtered_image = [filtered_image imageByApplyingTransform:CGAffineTransformMakeScale(scaleX, scaleY)];

it generates this log:

warning: could not execute support code to read Objective-C class data in the process. This may reduce the quality of type information available.

There's something in my method that works only on 12.0.1? Or maybe something wrong? How i can investigate more to solve that crash?

EDIT

in red i have:

MyQrCodeImageViewBig.image=qrimage;

with messagge:

Thread 1: EXC_BREAKPOINT (code=1, subcode=0x1a83e146c)

Answer 1

I see a lot of problems resulting from the [UIImage imageWithCIImage:] initializer. The main problem being that a CIImage does not actually contain any bitmap data. It needs to be rendered by a CIContext first. So the target you assign the UIImage to needs to know that it is backed by a CIImage that still needs rendering. Usually UIImageView handles this well, but I wouldn't trust it too much.

What you can do instead is to render the image yourself into a bitmap ( CGImage ) and initialize the UIImage with that instead. You need a CIContext for that, which I recommend you create somewhere outside this method once and re-use it every time you need to render an image (it's an expensive object):

self.context = [CIContext context];

Then in your method, you render the image like this:

CGImageRef cgImage = [self.context createCGImage:filtered_image fromRect:[filtered_image extent]];
UIImage* result_image = [UIImage imageWithCGImage:cgImage];