How to track multiple touches in Xcode

Question

Recently I\'m making an app that can drag multiple objects at the same time. I had tried to use UIPanGestureRecognizer to get the coordinates of finger touches,

Answer 1

I've struggled with the same problem for quite a long time and finally solved it. The following is the code in my DrawView.m, which is a subclass of UIView that is able to support drawings using drawRect:.

#import "DrawView.h"

#define MAX_TOUCHES 4

@interface DrawView() {

    bool touchInRect[MAX_TOUCHES];
    CGRect rects[MAX_TOUCHES];
    UITouch *savedTouches[MAX_TOUCHES];
}

@end

@implementation DrawView

-(id)initWithCoder:(NSCoder *)aDecoder {
    self = [super initWithCoder:aDecoder];
    if (self) {
        // Initialization code
        self.multipleTouchEnabled = YES;
        for (int i=0; i

I set the MAX_TOUCHES as 4, so there will be four objects on the screen. The basic concept of this is to store each UITouch ID in the savedTouches array when touchesBegan:: is called, and later compare each ID with the touches on screen when touchesMoved:: called.

Just paste the code into your .m file and it'll work. The sample result is shown here:

Hope this helps :)