Convert NSInvocation and NSArray containing arguments. Under Developing!

ConvertInvocationArguments.m

NSString *MTExtractStructName(NSString *typeEncodeString)
{
    NSArray *array = [typeEncodeString componentsSeparatedByString:@"="];
    NSString *typeString = array[0];
    int firstValidIndex = 0;
    for (int i = 0; i< typeString.length; i++) {
        char c = [typeString characterAtIndex:i];
        if (c == '{' || c=='_') {
            firstValidIndex++;
        }else {
            break;
        }
    }
    return [typeString substringFromIndex:firstValidIndex];
}

NSString *MTExtractTypeName(NSString *type)
{
    NSString *result = @"";
    NSArray<NSString *> *components = [type componentsSeparatedByString:@""];
    for (int i = 0; i < components.count; i ++) {
        if (i == 0) {
            result = [result stringByAppendingString:components[i]];
        }
        if (i > 0) {
            result = [result stringByAppendingString:components[i].capitalizedString];
        }
    }
    return result;
}

BOOL MTIsTypeQualifier(char c)
{
    if (c == 'r' || c == 'n' || c == 'N' || c == 'o' || c == 'O' || c == 'R' || c == 'V') {
        return YES;
    }
    return NO;
}



typedef NS_ENUM(NSUInteger, MTOperation) {
    MTOperationLoadArgumentsToInvocation,
    MTOperationStoreInvocationToArguments,
};

void MTUpdateArgumentsInvocation(NSInvocation *invocation, NSMutableArray *args, MTOperation operation)
{
    NSUInteger numberOfArguments = invocation.methodSignature.numberOfArguments;
    for (NSUInteger i = 2; i < numberOfArguments; i ++) {
        const char *argumentType = [invocation.methodSignature getArgumentTypeAtIndex:i];
        switch (MTIsTypeQualifier(argumentType[0]) ? argumentType[1] : argumentType[0]) {

                #define MT_FWD_ARG_CASE(_typeChar, _type, _typeCapitalizedString) \
                case _typeChar: {   \
                    _type arg;  \
                    if (MTOperationStoreInvocationToArguments == operation) { \
                        [invocation getArgument:&arg atIndex:i];    \
                        [args addObject:@(arg)]; \
                    } \
                    else if (MTOperationLoadArgumentsToInvocation == operation) { \
                        NSNumber *number = args[i - 2]; \
                        arg = [number _typeCapitalizedString##Value]; \
                        [invocation setArgument:&arg atIndex:i];  \
                    } \
                    break;  \
                }

                MT_FWD_ARG_CASE('c', char, char)
                MT_FWD_ARG_CASE('i', int, int)
                MT_FWD_ARG_CASE('s', short, short)
                MT_FWD_ARG_CASE('l', long, long)
                MT_FWD_ARG_CASE('q', long long, longLong)
                MT_FWD_ARG_CASE('C', unsigned char, unsignedChar)
                MT_FWD_ARG_CASE('I', unsigned int, unsignedInt)
                MT_FWD_ARG_CASE('S', unsigned short, unsignedShort)
                MT_FWD_ARG_CASE('L', unsigned long, unsignedLong)
                MT_FWD_ARG_CASE('Q', unsigned long long, unsignedLongLong)
                MT_FWD_ARG_CASE('f', float, float)
                MT_FWD_ARG_CASE('d', double, double)
                MT_FWD_ARG_CASE('B', BOOL, bool)
                case '*': {
                    const char *arg;
                    if (MTOperationStoreInvocationToArguments == operation) {
                        [invocation getArgument:&arg atIndex:i];
                        NSValue *value = [NSValue valueWithBytes:&arg objCType:@encode(char **)];
                        [args addObject:value];
                    }
                    else if (MTOperationLoadArgumentsToInvocation == operation) {
                        arg = [args[i - 2] UTF8String];
                        [invocation setArgument:&arg atIndex:2];
                    }
                    break;
                }
                case '@': {
                    __unsafe_unretained id arg;
                    if (MTOperationStoreInvocationToArguments == operation) {
                        [invocation getArgument:&arg atIndex:i];
                        if ([arg isKindOfClass:NSClassFromString(@"NSBlock")]) {
                            [args addObject:(arg ? [arg copy]: _nilObj)];
                        } else {
                            [args addObject:(arg ? arg: _nilObj)];
                        }
                    }
                    else if (MTOperationLoadArgumentsToInvocation == operation) {
                        arg = args[i - 2];
                        // set nil as invocation args
                        [invocation setArgument:&arg atIndex:i];
                    }
                    break;
                }
                case '#': {
                    Class arg;
                    if (MTOperationStoreInvocationToArguments == operation) {
                        [invocation getArgument:&arg atIndex:i];
                        [args addObject:arg];
                    }
                    else if (MTOperationLoadArgumentsToInvocation == operation) {
                        arg = args[i - 2];
                        [invocation setArgument:&arg atIndex:i];
                    }
                    break;
                }
                case ':': {
                    SEL selector;
                    if (MTOperationStoreInvocationToArguments == operation) {
                        [invocation getArgument:&selector atIndex:i];
                        NSString *selectorName = NSStringFromSelector(selector);
                        [args addObject:(selectorName ? selectorName: _nilObj)];
                    }
                    else if (MTOperationLoadArgumentsToInvocation == operation) {
                        NSString *selectorName = args[i - 2];
                        if (_nilObj == selectorName) {
                            selector = NSSelectorFromString(@"");
                        }
                        else {
                            selector = NSSelectorFromString(selectorName);
                        }
                        [invocation setArgument:&selector atIndex:i];
                    }
                    break;
                }

                #define MT_FWD_ARG_CTYPE \
                { \
                    void *arg; \
                    if (MTOperationStoreInvocationToArguments == operation) { \
                        [invocation getArgument:&arg atIndex:i]; \
                        NSValue *value = [NSValue valueWithBytes:&arg objCType:argumentType]; \
                        [args addObject:value]; \
                    } \
                    else if (MTOperationLoadArgumentsToInvocation == operation) { \
                        NSValue *value = args[i - 2]; \
                        if (@available(iOS 11, *)) { \
                            [value getValue:&arg size:sizeof(argumentType)]; \
                        } \
                        else { \
                            [value getValue:&arg]; \
                        } \
                        [invocation setArgument:&arg atIndex:i];  \
                    } \
                    break;\
                }

                case '[': MT_FWD_ARG_CTYPE
                case '{': {
                    NSString *structName = MTExtractStructName([NSString stringWithUTF8String:argumentType]);

                    #define MT_FWD_ARG_STRUCT(_type) \
                    if ([structName rangeOfString:@#_type].location != NSNotFound) {    \
                        _type arg; \
                        if (MTOperationStoreInvocationToArguments == operation) { \
                            [invocation getArgument:&arg atIndex:i];    \
                            NSValue *value = [NSValue valueWithBytes:&arg objCType:@encode(_type)]; \
                            [args addObject:value];  \
                            } \
                        else if (MTOperationLoadArgumentsToInvocation == operation) { \
                            NSValue *value = args[i - 2]; \
                            if (@available(iOS 11, *)) { \
                                [value getValue:&arg size:sizeof(_type)]; \
                            } \
                            else { \
                                [value getValue:&arg]; \
                            } \
                            [invocation setArgument:&arg atIndex:i];  \
                        } \
                        break; \
                    }

                    MT_FWD_ARG_STRUCT(CGPoint)
                    MT_FWD_ARG_STRUCT(CGVector)
                    MT_FWD_ARG_STRUCT(CGSize)
                    MT_FWD_ARG_STRUCT(CGRect)
                    MT_FWD_ARG_STRUCT(CGAffineTransform)
                    MT_FWD_ARG_STRUCT(UIEdgeInsets)
                    MT_FWD_ARG_STRUCT(NSDirectionalEdgeInsets)
                    MT_FWD_ARG_STRUCT(UIOffset)
                    MT_FWD_ARG_STRUCT(NSRange)
                    MT_FWD_ARG_CTYPE

                    break;
                }
                case '(': MT_FWD_ARG_CTYPE
                case 'b': MT_FWD_ARG_CTYPE
                case '^': {
                    void *arg;
                    if (MTOperationStoreInvocationToArguments == operation) {
                        [invocation getArgument:&arg atIndex:i];
                        [args addObject:[NSValue value:arg withObjCType:argumentType]];
                    }
                    else if (MTOperationLoadArgumentsToInvocation == operation) {
                        NSValue *value = args[i - 2];
                        // TODO: get type pointer name
//                        if (@available(iOS 11, *)) {
//                            [value getValue:&arg size:sizeof()];
//                        }
//                        else {
                            [value getValue:&arg];
//                        }
                        [invocation setArgument:&arg atIndex:i];
                    }
                    break;
                }
                case '?':
                default: {
                    NSLog(@"error type %s", argumentType);
                    break;
                }
        }
    }
}

Hello, thanks for sharing and I have obtained a lot of help from you. I have a question, why __unsafe_unretained is necessary for object type? I encountered an EXC_BAD_ACCESS while waiting for an expectation in unit test while __unsafe_unretained is not presented, and I am very puzzled. Thanks again!