如何在Unity中实现iOS设备的滑动手势检测？

一、调用iOS原生手势识别功能 #

可以通过Unity的原生插件机制，直接调用iOS系统的UIGestureRecognizer实现系统级滑动检测，步骤如下：

1. 编写iOS原生插件代码（Objective-C）
   创建.mm文件（如iOSGesturePlugin.mm），放在Unity项目的Assets/Plugins/iOS目录下：

#import <UIKit/UIKit.h>

@interface iOSGestureHandler : NSObject
@property (nonatomic, strong) UISwipeGestureRecognizer *leftSwipe;
@property (nonatomic, strong) UISwipeGestureRecognizer *rightSwipe;
@property (nonatomic, strong) UISwipeGestureRecognizer *upSwipe;
@property (nonatomic, strong) UISwipeGestureRecognizer *downSwipe;
@end

@implementation iOSGestureHandler

+ (instancetype)sharedInstance {
    static iOSGestureHandler *instance = nil;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        instance = [[iOSGestureHandler alloc] init];
        [instance setupGestures];
    });
    return instance;
}

- (void)setupGestures {
    UIWindow *window = [[UIApplication sharedApplication] keyWindow];
    
    _leftSwipe = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleLeftSwipe:)];
    _leftSwipe.direction = UISwipeGestureRecognizerDirectionLeft;
    [window addGestureRecognizer:_leftSwipe];
    
    _rightSwipe = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleRightSwipe:)];
    _rightSwipe.direction = UISwipeGestureRecognizerDirectionRight;
    [window addGestureRecognizer:_rightSwipe];
    
    _upSwipe = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleUpSwipe:)];
    _upSwipe.direction = UISwipeGestureRecognizerDirectionUp;
    [window addGestureRecognizer:_upSwipe];
    
    _downSwipe = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleDownSwipe:)];
    _downSwipe.direction = UISwipeGestureRecognizerDirectionDown;
    [window addGestureRecognizer:_downSwipe];
}

- (void)handleLeftSwipe:(UISwipeGestureRecognizer *)gesture {
    UnitySendMessage("GestureReceiver", "OnLeftSwipe", "");
}

- (void)handleRightSwipe:(UISwipeGestureRecognizer *)gesture {
    UnitySendMessage("GestureReceiver", "OnRightSwipe", "");
}

- (void)handleUpSwipe:(UISwipeGestureRecognizer *)gesture {
    UnitySendMessage("GestureReceiver", "OnUpSwipe", "");
}

- (void)handleDownSwipe:(UISwipeGestureRecognizer *)gesture {
    UnitySendMessage("GestureReceiver", "OnDownSwipe", "");
}

@end

extern "C" {
    void _InitiOSGestures() {
        [iOSGestureHandler sharedInstance];
    }
}

2. 编写C#调用脚本
   创建iOSGestureWrapper.cs，用来初始化插件：

using UnityEngine;

public class iOSGestureWrapper : MonoBehaviour
{
    [System.Runtime.InteropServices.DllImport("__Internal")]
    private static extern void _InitiOSGestures();

    void Start()
    {
        #if UNITY_IOS && !UNITY_EDITOR
            _InitiOSGestures();
        #endif
    }
}

3. 创建回调接收脚本
   创建GestureReceiver.cs，挂载到名为GestureReceiver的GameObject上：

using UnityEngine;

public class GestureReceiver : MonoBehaviour
{
    public void OnLeftSwipe()
    {
        Debug.Log("iOS原生左滑触发");
        // 编写左滑逻辑
    }

    public void OnRightSwipe()
    {
        Debug.Log("iOS原生右滑触发");
        // 编写右滑逻辑
    }

    public void OnUpSwipe()
    {
        Debug.Log("iOS原生上滑触发");
        // 编写上滑逻辑
    }

    public void OnDownSwipe()
    {
        Debug.Log("iOS原生下滑触发");
        // 编写下滑逻辑
    }
}

注意：在Unity插件设置中，将iOSGesturePlugin.mm的平台限定为iOS。

二、第三方库/插件推荐 #

1. Unity官方Input System包 #

替代旧版Input Manager，原生支持触摸手势：

• 通过Package Manager安装Input System包
• 创建Input Action Asset，添加Swipe动作并配置阈值参数
• 脚本绑定示例：

using UnityEngine;
using UnityEngine.InputSystem;

public class SwipeDetector : MonoBehaviour
{
    public InputAction swipeAction;

    void OnEnable()
    {
        swipeAction.Enable();
        swipeAction.performed += OnSwipePerformed;
    }

    void OnDisable()
    {
        swipeAction.performed -= OnSwipePerformed;
        swipeAction.Disable();
    }

    void OnSwipePerformed(InputAction.CallbackContext context)
    {
        Vector2 swipeDelta = context.ReadValue<Vector2>();
        Debug.Log($"滑动方向：{swipeDelta}");
        // 根据swipeDelta判断滑动方向
    }
}

2. Lean Touch #

轻量级触摸处理插件，支持多种手势：

• 在Unity Asset Store安装后，挂载LeanTouch组件
• 监听滑动事件示例：

using UnityEngine;
using Lean.Touch;

public class LeanSwipeHandler : MonoBehaviour
{
    void OnEnable()
    {
        LeanTouch.OnSwipe += OnSwipe;
    }

    void OnDisable()
    {
        LeanTouch.OnSwipe -= OnSwipe;
    }

    void OnSwipe(LeanFinger finger)
    {
        Vector2 swipeDir = finger.SwipeScreenDelta;
        if (Mathf.Abs(swipeDir.x) > Mathf.Abs(swipeDir.y))
        {
            Debug.Log(swipeDir.x > 0 ? "右滑" : "左滑");
        }
        else
        {
            Debug.Log(swipeDir.y > 0 ? "上滑" : "下滑");
        }
    }
}

3. TouchKit #

专注触摸手势的插件，提供开箱即用的滑动检测API，配置简单，适合新手快速集成。

三、可靠的自定义滑动检测实现 #

修正之前的自定义算法问题，加入阈值过滤误触和长按：

using UnityEngine;

public class CustomSwipeDetector : MonoBehaviour
{
    public float swipeThreshold = 50f; // 滑动位移阈值（像素）
    public float timeThreshold = 0.5f; // 滑动时间阈值（秒）

    private Vector2 touchStartPos;
    private float touchStartTime;

    void Update()
    {
        if (Input.touchCount == 1)
        {
            Touch touch = Input.GetTouch(0);
            switch (touch.phase)
            {
                case TouchPhase.Began:
                    touchStartPos = touch.position;
                    touchStartTime = Time.time;
                    break;

                case TouchPhase.Ended:
                    float timeElapsed = Time.time - touchStartTime;
                    if (timeElapsed > timeThreshold) break;

                    Vector2 swipeDelta = touch.position - touchStartPos;
                    if (Mathf.Abs(swipeDelta.x) > swipeThreshold || Mathf.Abs(swipeDelta.y) > swipeThreshold)
                    {
                        if (Mathf.Abs(swipeDelta.x) > Mathf.Abs(swipeDelta.y))
                        {
                            Debug.Log(swipeDelta.x > 0 ? "自定义右滑" : "自定义左滑");
                        }
                        else
                        {
                            Debug.Log(swipeDelta.y > 0 ? "自定义上滑" : "自定义下滑");
                        }
                    }
                    break;
            }
        }
    }
}

内容的提问来源于stack exchange，提问作者Zaxoosh