根據專案需求，需要一個IamgeView達到上下拖動來改變下方View高度的需求，現有手勢中UIPanGestureRecognizer可以實現可以實現起上下左右拖動。
思考：在拖動時是否可以通過判斷x軸和y軸的移動距離來判斷是左右還是上下移動，再來禁止其左右移動。 程式碼部分：
//可拖動ImageView
- (void)setDragImageView{
self.dragImageView.userInteractionEnabled = YES;
UIPanGestureRecognizer *panGesture = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(panGestureClick:)];
[self.dragImageView addGestureRecognizer:panGesture];
}
- (void)panGestureClick:(UIPanGestureRecognizer *)panGest{
CGPoint panGesturePoint = [panGest translationInView:self.allTitleLowerView];
panGest.view.center = CGPointMake(panGest.view.center.x + 0, panGest.view.center.y - panGesturePoint.y);
[self.answersViewHeight setConstant: self.answersViewHeight.constant - panGesturePoint.y ];
if (panGest.state == UIGestureRecognizerStateFailed || panGest.state == UIGestureRecognizerStateEnded) {
if (panGest.view.center.y < 20) {
panGest.view.center = CGPointMake(panGest.view.center.x, 21);
[self.answersViewHeight setConstant: kScreenHeight - 44 - 40];
}
}
//重置拖拽手勢
[panGest setTranslation:CGPointZero inView:self.view];
}
複製程式碼最後呈現效果：
PS：在網上百度時找到了他人方法需要重新自定義一個手勢繼承 UIPanGestureRecognizer，使用：比較底層的
- (void)touchesMoved:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
複製程式碼最終呈現出得效果一樣