创建只有上下或者左右手势的UIPanGestureRecognizer

  • PanGesture.h
#import <UIKit/UIKit.h>

NS_ASSUME_NONNULL_BEGIN

typedef NS_ENUM(NSInteger, PanDirection) {
    PanDirectionVertical,
    PanDirectionHorizontal,
};

@interface PanGesture : UIPanGestureRecognizer

@property (nonatomic, assign) PanDirection direction;

@end

NS_ASSUME_NONNULL_END
  • PanGesture.m
#import "PanGesture.h"

NSInteger const static kDirectionPanThreshold = 5;

@interface PanGesture() {
    BOOL _drag;
    int _moveX;
    int _moveY;
}
@end
@implementation PanGesture

- (void)touchesMoved:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
    [super touchesMoved:touches withEvent:event];
    if (self.state == UIGestureRecognizerStateFailed) {
        return;
    }
    CGPoint nowPoint = [[touches anyObject] locationInView:self.view];
    CGPoint prevPoint = [[touches anyObject] previousLocationInView:self.view];
    _moveX += prevPoint.x - nowPoint.x;
    _moveY += prevPoint.y - nowPoint.y;
    if (!_drag) {
        if (abs(_moveX) > kDirectionPanThreshold) {
            if (self.direction == PanDirectionVertical) {
                self.state = UIGestureRecognizerStateFailed;
            } else {
                _drag = YES;
            }
        } else if (abs(_moveY) > kDirectionPanThreshold) {
            if (self.direction == PanDirectionHorizontal) {
                self.state = UIGestureRecognizerStateFailed;
            } else {
                _drag = YES;
            }
        }
    }
}

- (void)reset {
    [super reset];
    _drag = NO;
    _moveX = 0;
    _moveY = 0;
}

@end