Xcode：需要幫助移動屏幕邊界內的圖像

Question

我跟着一個關於在屏幕上用手勢識別器拖動多個圖像的指南，但我有一個問題。我想要將圖像拖入iPad或iPhone屏幕的邊界內。我使用的代碼估計圖像的中心，因此當達到邊界時圖像的一半會越過屏幕。你能幫我解決這個問題嗎？

- (IBAction)handlePan:(UIPanGestureRecognizer *)recognizer { 

CGPoint translation = [recognizer translationInView:self.view]; 
recognizer.view.center = CGPointMake(recognizer.view.center.x + translation.x, 
            recognizer.view.center.y + translation.y); 
[recognizer setTranslation:CGPointMake(0, 0) inView:self.view]; 

if (recognizer.state == UIGestureRecognizerStateEnded) { 

    CGPoint velocity = [recognizer velocityInView:self.view]; 
    CGFloat magnitude = sqrtf((velocity.x * velocity.x) + (velocity.y * velocity.y)); 
    CGFloat slideMult = magnitude/200; //original divider 200 
    NSLog(@"magnitude: %f, slideMult: %f", magnitude, slideMult); 

    float slideFactor = 0.1 * slideMult /4; // Increase for more of a slide (original doesn't have a divider) 
    CGPoint finalPoint = CGPointMake(recognizer.view.center.x + (velocity.x * slideFactor), 
            recognizer.view.center.y + (velocity.y * slideFactor)); 
    finalPoint.x = MIN(MAX(finalPoint.x, 0), self.view.bounds.size.width); 
    finalPoint.y = MIN(MAX(finalPoint.y, 0), self.view.bounds.size.height); 

    [UIView animateWithDuration:slideFactor*2 delay:0 options:UIViewAnimationOptionCurveEaseOut animations:^{ 
     recognizer.view.center = finalPoint; 
    } completion:nil]; 
    } 
} 

Answer 1

嗯，我設法找出解決我的問題。我將圖像的寬度和高度除以2。在我的情況下，結果是100和70.其餘的可以在代碼框中看到：

finalPoint.x = MIN(MAX(finalPoint.x, 70), self.view.bounds.size.width-70); 
finalPoint.y = MIN(MAX(finalPoint.y, 100), self.view.bounds.size.height-100);