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我正在尝试向我的 UITableViewCells 添加一个平底锅，并且我有以下代码。由于某种原因，即使我从情节提要中引用了该类并设置了委托，也从未调用过 handlepan 方法。

    #import <QuartzCore/QuartzCore.h>
    #import "TaskTableViewCell.h"

@implementation TaskTableViewCell {
    CAGradientLayer* _gradientLayer;
    CGPoint _originalCenter;
    BOOL _deleteOnDragRelease;
}

- (id)initWithStyle:(UITableViewCellStyle)style reuseIdentifier:(NSString *)reuseIdentifier
{
    self = [super initWithStyle:style reuseIdentifier:reuseIdentifier];
    if (self) {
        // add a layer that overlays the cell adding a subtle gradient effect
        _gradientLayer = [CAGradientLayer layer];
        _gradientLayer.frame = self.bounds;
        _gradientLayer.colors = @[(id)[[UIColor colorWithWhite:1.0f alpha:0.2f] CGColor],
                                  (id)[[UIColor colorWithWhite:1.0f alpha:0.1f] CGColor],
                                  (id)[[UIColor clearColor] CGColor],
                                  (id)[[UIColor colorWithWhite:0.0f alpha:0.1f] CGColor]];
        _gradientLayer.locations = @[@0.00f, @0.01f, @0.95f, @1.00f];
        [self.layer insertSublayer:_gradientLayer atIndex:0];

        // add a pan recognizer
        UIPanGestureRecognizer* recognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(handlePan:)];
        recognizer.delegate = self;
        [self addSubview:self.taskTextLabel];
        [self addSubview:self.priorityView];
        [self addGestureRecognizer:recognizer];
    }
    return self;
}

-(void)layoutSubviews {
    [super layoutSubviews];
    _gradientLayer.frame = self.bounds;
}

#pragma mark - horizontal pan gesture methods
-(BOOL)gestureRecognizerShouldBegin:(UIPanGestureRecognizer *)gestureRecognizer {
    CGPoint translation = [gestureRecognizer translationInView:[self superview]];
    // Check for horizontal gesture
    if (fabsf(translation.x) > fabsf(translation.y)) {
        return YES;
    }
    return NO;
}

-(void)handlePan:(UIPanGestureRecognizer *)recognizer {
    NSLog(@"Pan");
    // 1
    if(recognizer.state == UIGestureRecognizerStateBegan) {
        // if the gesture has just started, record the current centre location
        _originalCenter = self.center;
    }

    // 2
    if(recognizer.state == UIGestureRecognizerStateChanged) {
        // translate the center
        CGPoint translation = [recognizer translationInView:self];
        self.center = CGPointMake(_originalCenter.x + translation.x, _originalCenter.y);
        // determine wheter the item has been dragged far enough to initiate a delete / complete
        _deleteOnDragRelease = self.frame.origin.x < -self.frame.size.width / 2;
    }

    // 3
    if (recognizer.state == UIGestureRecognizerStateEnded) {
        // the frame this cell would have had before being dragged
        CGRect originalFrame = CGRectMake(0, self.frame.origin.y, self.bounds.size.width, self.bounds.size.height);

        if(!_deleteOnDragRelease) {
            // if the item is not being deleted, snap back to the original location
            [UIView animateWithDuration:0.2 animations:^{
                self.frame = originalFrame;
                }
             ];
        }
    }
}

这是该类的头文件。

#import <UIKit/UIKit.h>
#import "Task.h"

@interface TaskTableViewCell : UITableViewCell <UIGestureRecognizerDelegate>

@property (strong, nonatomic) Task *task;
@property (weak, nonatomic) IBOutlet UIView *priorityView;
@property (weak, nonatomic) IBOutlet UILabel *taskTextLabel;

@end

另外我想补充一点，我使用的是 Storyboards 而不是 xib 文件。

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