Move UIView with relation to touch

i'm trying to move a UIView with relation to the user's touches.

Here's what I have at the moment:

int oldX, oldY;
BOOL dragging;

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

    UITouch *touch = [[event allTouches] anyObject];
    CGPoint touchLocation = [touch locationInView:self.view];

    if (CGRectContainsPoint(window.frame, touchLocation)) {
        dragging = YES;
        oldX = touchLocation.x;
        oldY = touchLocation.y;
    }

}

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
    UITouch *touch = [[event allTouches] anyObject];
    CGPoint touchLocation = [touch locationInView:self.view];

    if (CGRectContainsPoint(window.frame, touchLocation) && dragging) {
        CGRect frame;
        frame.origin.x = (window.frame.origin.x + touchLocation.x - oldX);
        frame.origin.y = (window.frame.origin.y + touchLocation.y - oldY);
        window.frame = frame;

    }

}

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
    dragging = NO;
}

The view keeps flickering from one location to another, and I don't know what else to do.

Any help appreciated.