a gross way to use raw iokit events to detect pinch gestures

code.mm

#import <UIKit/UIKit.h>
#include <IOKit/hid/IOHIDEventSystem.h>
#include <IOKit/hid/IOHIDEventSystemClient.h>
#include "CDTContextHostProvider.h"
#include <stdio.h>
#include <dlfcn.h>

UIView *contextView;

int IOHIDEventSystemClientSetMatching(IOHIDEventSystemClientRef client, CFDictionaryRef match);
CFArrayRef IOHIDEventSystemClientCopyServices(IOHIDEventSystemClientRef, int);
typedef struct __IOHIDServiceClient * IOHIDServiceClientRef;
int IOHIDServiceClientSetProperty(IOHIDServiceClientRef, CFStringRef, CFNumberRef);
typedef void* (*clientCreatePointer)(const CFAllocatorRef);
extern "C" void BKSHIDServicesCancelTouchesOnMainDisplay();


void touch_event(void* target, void* refcon, IOHIDServiceRef service, IOHIDEventRef event) {

    if (IOHIDEventGetType(event) == kIOHIDEventTypeDigitizer) {

        //get child events (individual finger)
        NSArray *children = (NSArray *)IOHIDEventGetChildren(event);
        if ([children count] == 2) { //pinch

            CGFloat p1x = IOHIDEventGetFloatValue((__IOHIDEvent *)children[0], (IOHIDEventField)kIOHIDEventFieldDigitizerX);
            CGFloat p1y = IOHIDEventGetFloatValue((__IOHIDEvent *)children[0], (IOHIDEventField)kIOHIDEventFieldDigitizerY);
            CGFloat p2x = IOHIDEventGetFloatValue((__IOHIDEvent *)children[1], (IOHIDEventField)kIOHIDEventFieldDigitizerX);
            CGFloat p2y = IOHIDEventGetFloatValue((__IOHIDEvent *)children[1], (IOHIDEventField)kIOHIDEventFieldDigitizerY);
            CGFloat diff = sqrt(((p2x - p1x) * (p2x - p1x)) + ((p2y - p1y) * (p2y - p1y)));
            diff = (diff > 1) ? 1 : diff;

            NSLog(@"pinch : %f", diff);

            //do stuff
            if (contextView) {

                //block other touches
                BKSHIDServicesCancelTouchesOnMainDisplay();

                //resize app window
                [contextView setTransform:CGAffineTransformMakeScale(diff, diff)];
            }
            

        }
    }
}

%hook SBLockScreenManager

- (void)_finishUIUnlockFromSource:(int)source withOptions:(id)options {

    %orig;

    //my IOKit's symbol table is fucked so we doin lookups
    clientCreatePointer clientCreate;
    void *handle = dlopen(0, 9);
    *(void**)(&clientCreate) = dlsym(handle,"IOHIDEventSystemClientCreate");
    IOHIDEventSystemClientRef ioHIDEventSystem = (__IOHIDEventSystemClient *)clientCreate(kCFAllocatorDefault);
    IOHIDEventSystemClientScheduleWithRunLoop(ioHIDEventSystem, CFRunLoopGetCurrent(), kCFRunLoopDefaultMode);
    IOHIDEventSystemClientRegisterEventCallback(ioHIDEventSystem, (IOHIDEventSystemClientEventCallback)touch_event, NULL, NULL);

    //throw a weather host view up on unlock to demonstrate
    CDTContextHostProvider *contextProvider = [[CDTContextHostProvider alloc] init];
    contextView = [contextProvider hostViewForApplicationWithBundleID:@"com.apple.weather"];
    [contextProvider setStatusBarHidden:@(1) onApplicationWithBundleID:@"com.apple.weather"];
    [contextView setTransform:CGAffineTransformMakeScale(.6, .6)];

    [[[UIApplication sharedApplication] keyWindow] addSubview:contextView];

}


%end