Question

I’m trying to store UITouches in a dictionary or array and having some trouble. Storing CGPoints works fine, but storing UITouches not.

Further explanation: initializing array when touches begin, store each UITouch in an array, when touches end I want to output the array. I have been looking for some time, but I haven’t found any sample code to do this.

NSMutableArray *touchesArray;
NSMutableArray *pointArray;

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{

    touchesArray = [[NSMutableArray alloc] init];

    pointArray = [[NSMutableArray alloc] init];
}

-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event{

    UITouch *touch = [touches anyObject];
    CGPoint currentPoint = [touch locationInView:self];
     [pointArray addObject:[NSValue valueWithCGPoint: currentPoint]];

    [touchesArray addObject:[NSValue valueWithPointer:(__bridge const void *)(touch)]];

    for (UITouch *touch in touches)
    {
        NSLog(@"x location %f",[touch locationInView:self].x);
    }


}

-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event{        

    for (UITouch *touch in touches)
    {        
        NSLog(@"%f",[touch locationInView:self].x);
    }

    for(id p in pointArray){
        NSValue *val = p;
        CGPoint point = [val CGPointValue];
        NSLog(@"%f",point.x);
    }

    //ERROR!
    for(id p in touchesArray){
        NSValue *val = p;
        UITouch *t = (UITouch*) p;
        NSLog(@"%@",[t timestamp]);
    }

}

Answer 1

Using a wrapper object worked for me. UITouch always pointed to the same adress.

#import "TouchInfo.h"

@implementation TouchInfo

@synthesize timestamp;
@synthesize location;

@end


-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event{
int ns = [touches count];
NSLog(@"number of touches  %i",ns);
for(UITouch *touch in touches)
{
    NSNumber *val = [NSNumber numberWithFloat:[touch timestamp]];        
    TouchInfo *touchInfo = [[TouchInfo alloc] init];
    touchInfo.location = [touch locationInView:self];
    touchInfo.timestamp = [touch timestamp];
}
}

-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event{

int nt = [touchesArray count];
for (int i = 0; i < nt; i++){
    TouchInfo *touchInfo = (TouchInfo*)[touchesArray objectAtIndex:i];
    NSLog(@"%f  %f   %f",touchInfo.timestamp,touchInfo.location.x,touchInfo.location.y);    

}
}