手勢(shì)沖突處理

• 1、自定義手勢(shì)優(yōu)先級(jí)
• 2、阻止手勢(shì)向響應(yīng)鏈傳遞執(zhí)行
• 3、實(shí)現(xiàn)協(xié)議方法 `UIGestureRecognizerDelegate` 控制手勢(shì)沖突
• 4、自定義手勢(shì)

手勢(shì)沖突主要的三種解決思路：

• 設(shè)置手勢(shì)優(yōu)先級(jí) requireGestureRecognizerToFail:
• 阻止手勢(shì)向事件傳遞鏈執(zhí)行 cancelsTouchesInView、delaysTouchesBegan
• 實(shí)現(xiàn)協(xié)議方法 UIGestureRecognizerDelegate
• （自定義手勢(shì)）重寫父類中的個(gè)別方法 @interface UIGestureRecognizer (UIGestureRecognizerProtected)

1、自定義手勢(shì)優(yōu)先級(jí)

場(chǎng)景一：
自定義多手勢(shì)沖突。例如我們?cè)O(shè)置的單次點(diǎn)擊、雙擊和三次點(diǎn)擊手勢(shì)，需要設(shè)置優(yōu)先識(shí)別三擊手勢(shì)，識(shí)別失敗后再識(shí)別雙擊手勢(shì)；同理，雙擊手勢(shì)識(shí)別失敗后再識(shí)別單擊手勢(shì)。

/// 自定義多手勢(shì)沖突func test_1() {let oneGes = UITapGestureRecognizer(target: self, action: #selector(oneTap(tapGes:)))oneGes.numberOfTapsRequired = 1self.scrollVeiw.addGestureRecognizer(oneGes)let twoGes = UITapGestureRecognizer(target: self, action: #selector(twoTap(tapGes:)))twoGes.numberOfTapsRequired = 2self.scrollVeiw.addGestureRecognizer(twoGes)let threeGes = UITapGestureRecognizer(target: self, action: #selector(threeTap(tapGes:)))threeGes.numberOfTapsRequired = 3self.scrollVeiw.addGestureRecognizer(threeGes)// 優(yōu)先級(jí)設(shè)置oneGes.require(toFail: twoGes)twoGes.require(toFail: threeGes)}@objc func oneTap(tapGes: UITapGestureRecognizer) {print("=================> oneTap")}@objc func twoTap(tapGes: UITapGestureRecognizer) {print("=================> twoTap")}@objc func threeTap(tapGes: UITapGestureRecognizer) {print("=================> threeTap")}

2、阻止手勢(shì)向響應(yīng)鏈傳遞執(zhí)行

當(dāng)自定義手勢(shì)和系統(tǒng)手勢(shì)沖突，可以使用手勢(shì)的兩個(gè)屬性：cancelsTouchesInView、delaysTouchesBegan進(jìn)行處理。
例如：頁(yè)面添加自定義手勢(shì) UIPanGestureRecognizer，與頁(yè)面上的系統(tǒng)手勢(shì) touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) 回調(diào)方法沖突，可利用該屬性屏蔽掉系統(tǒng)手勢(shì)。

• cancelsTouchesInView（是否取消向事件響應(yīng)鏈傳遞）：
  默認(rèn) YES，自定義的手勢(shì)響應(yīng)后，系統(tǒng)手勢(shì)不再響應(yīng)，但自定義手勢(shì)識(shí)別前，會(huì)先執(zhí)行系統(tǒng)手勢(shì)。
  設(shè)置為 NO 后，自定義手勢(shì)和系統(tǒng)手勢(shì)會(huì)同時(shí)識(shí)別響應(yīng)。
• delaysTouchesBegan（延遲響應(yīng)鏈的識(shí)別）：
  默認(rèn) NO，先執(zhí)行響應(yīng)鏈中的方法（系統(tǒng)方法），識(shí)別到自定義手勢(shì)后，不再執(zhí)行系統(tǒng)方法。
  設(shè)置為 YES 后，優(yōu)先識(shí)別自定義手勢(shì)，當(dāng)自定義手勢(shì)識(shí)別失敗后才會(huì)響應(yīng)系統(tǒng)方法

屏蔽掉系統(tǒng)方法，我們只需要將屬性 delaysTouchesBegan 設(shè)置為 YES 即可：

// MARK: - 阻止手勢(shì)向事件傳遞鏈傳遞func test_2() {let panGes = UIPanGestureRecognizer(target: self, action: #selector(panGestureAction(panGes:)))// 阻止手勢(shì)向事件傳遞鏈執(zhí)行 默認(rèn)是 YES// panGes.cancelsTouchesInView = false// 延遲手勢(shì)向事件傳遞鏈執(zhí)行 默認(rèn)是 NOpanGes.delaysTouchesBegan = trueself.view.addGestureRecognizer(panGes)}@objc func panGestureAction(panGes: UIPanGestureRecognizer) {let point = panGes.location(in: self.view)print("********************")print("W ==> \(point.x)")print("H ==> \(point.y)")}override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {let point = touches.first?.location(in: self.view)print("=====================")print("W ==> \(String(describing: point?.x))")print("H ==> \(String(describing: point?.y))")}

3、實(shí)現(xiàn)協(xié)議方法 UIGestureRecognizerDelegate 控制手勢(shì)沖突

常用的是第二個(gè)協(xié)議方法 gestureRecognizer: shouldRecognizeSimultaneouslyWithGestureRecognizer:

//手指觸摸屏幕后回調(diào)的方法，返回NO則不再進(jìn)行手勢(shì)識(shí)別，方法觸發(fā)等 - (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch; //開始進(jìn)行手勢(shì)識(shí)別時(shí)調(diào)用的方法，返回NO則結(jié)束，不再觸發(fā)手勢(shì) - (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer; //是否支持多時(shí)候觸發(fā)，返回YES，則可以多個(gè)手勢(shì)一起觸發(fā)方法，返回NO則為互斥 - (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer; //下面這個(gè)兩個(gè)方法也是用來(lái)控制手勢(shì)的互斥執(zhí)行的 //這個(gè)方法返回YES，第一個(gè)手勢(shì)和第二個(gè)互斥時(shí)，第一個(gè)會(huì)失效 - (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRequireFailureOfGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer NS_AVAILABLE_IOS(7_0); //這個(gè)方法返回YES，第一個(gè)和第二個(gè)互斥時(shí)，第二個(gè)會(huì)失效 - (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldBeRequiredToFailByGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer NS_AVAILABLE_IOS(7_0);

4、自定義手勢(shì)

系統(tǒng)提供給我們的手勢(shì)可以滿足絕大多數(shù)的業(yè)務(wù)場(chǎng)景需求，對(duì)于特殊情況，可能需要用到自定義的手勢(shì)。
繼承 UIGestureRecognizer ,并重寫以下方法：

override func reset() {super.reset()state = .possible}override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent) {super.touchesBegan(touches, with: event)state = .began}override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent) {super.touchesBegan(touches, with: event)}override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent) {super.touchesEnded(touches, with: event)state = .ended}override func touchesCancelled(_ touches: Set<UITouch>, with event: UIEvent) {super.touchesCancelled(touches, with: event)state = .changed}

根據(jù)其它博客內(nèi)容提示，如需修改手勢(shì)的 state 屬性，需要引入 import UIKit.UIGestureRecognizerSubclass,但根據(jù)實(shí)測(cè)，未引入也不會(huì)報(bào)錯(cuò)。

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