quentinfasquel

#import "objc_tryCatch.h"

NSException * _Nullable objc_tryCatch(void (^ _Nonnull block)(void)) {
    @try {
        block();
        return nil;
    } @catch (NSException *exception) {
        return exception;
    }
}

quentinfasquel

// Given a block `let mayRaiseAnException: () -> Void`

if let exception = objc_tryCatch(mayRaiseAnException) {
  // Here is your caugth exception
}

quentinfasquel

// MyFailingObject.m

@implementation MyFailingObject

- (void)throwException {
  @throw [NSException exceptionWithName:NSGenericException
                                 reason:@"An exception on purpose"                                   
                               userInfo:nil];
}

quentinfasquel

// CatchingException.swift

{
    let failingObject = MyFailingObject()

    if let exception = objc_tryCatch({ failingObject.throwException() }) {
        // Here we caught the exception, but we actually leaked failingObject
    }

    // Let's check that it's actually leaking

quentinfasquel

#import "LeakTest.h"
#import "FailingObject.h"

@interface LeakTest ()
@property (nonatomic, strong) FailingObject *object;
@end

@implementation LeakTest

- (void)performFailure {

quentinfasquel

import CoreImage

class AlphaFrameFilter: CIFilter {
  static var kernel: CIColorKernel? = {
    return CIColorKernel(source: """
kernel vec4 alphaFrame(__sample s, __sample m) {
  return vec4( s.rgb, m.r );
}
""")
  }()

quentinfasquel

#include <metal_stdlib>
using namespace metal;
#include <CoreImage/CoreImage.h>

extern "C" {
    namespace coreimage {
       float4 doNothing(sampler src) {
           return src.sample(src.coord());
       }
    }

quentinfasquel

import CoreImage
import Metal

private func defaultMetalLibrary() throws -> Data {
    let url = Bundle.main.url(forResource: "default", withExtension: "metallib")!
    return try Data(contentsOf: url)
}

extension CIKernel {
    /// Init CI kernel with just a `functionName` directly from default metal library

quentinfasquel

let myKernel = try CIKernel(functionName: "doNothing")

quentinfasquel

guard let filter = CIFitler(name: "CIBlendWithMask") else {
    // Could not find the built-in filter
    return nil
}

let backgroundImage = CIImage(color: .clear).cropped(to: inputImage.extent)
filter.setValue(backgroundImage, forKey: kCIInputBackgroundImageKey)
filter.setValue(inputImage, forKey: kCIInputImageKey)
filter.setValue(maskImage, forKey: kCIInputMaskImageKey)
return filter.outputImage