滑动手势滑动 UIView

Question

我想做滑动手势来连续滑动 UIView 并从中获取数据。考虑每个 UIView 中的每个单词。我将数据存储在数组中，并在转换时打印在 UIView 的标签中。但是，当我在显示所有数据后尝试滑动时，程序停止工作。我的项目没有显示任何错误。请帮我解决一下。

这是我的数组：

addArray = [[NSMutableArray alloc]initWithCapacity:4];
[addArray insertObject:@"10" atIndex:0];
[addArray insertObject:@"20" atIndex:1];
[addArray insertObject:@"30" atIndex:2];
[addArray insertObject:@"40" atIndex:3];

flippedArray = [[NSMutableArray alloc] initWithCapacity:4];
[flippedArray insertObject:@"100" atIndex:0];
[flippedArray insertObject:@"200" atIndex:1];
[flippedArray insertObject:@"300" atIndex:2];
[flippedArray insertObject:@"400" atIndex:3];

这是我的手势识别器编码：

-(void)swipegesture:(UISwipeGestureRecognizer *)recognizer{

    CGPoint location = [recognizer locationInView:additionalView];   
    if (recognizer.direction==UISwipeGestureRecognizerDirectionLeft) 
    {
        if (increment<[addArray count]) 
        {
            NSLog(@"%d",[addArray count]);
            increment++;
            if(increment==[addArray count])
            {
                NSLog(@"Fail");
                //[recognizer requireGestureRecognizerToFail:swipeGesture];
                [recognizer setEnabled:NO];
            }
            else
            {
                additionalLabel.text=[[NSString alloc] initWithFormat:@"%@",
                                         [addArray objectAtIndex:increment]];
                flippedLabel.text = [[NSString alloc] initWithFormat:@"%@",
                                         [flippedArray objectAtIndex:increment]];
                NSLog(@"increment %d",increment);
                [UIView animateWithDuration:0.55 animations:^{
                    [UIView setAnimationDelay:0.2];
                }];
                CATransition *animation = [CATransition animation];
                [animation setType:kCATransitionPush];
                [animation setSubtype:kCATransitionFromRight];
                [animation setTimingFunction:[CAMediaTimingFunction
                               functionWithName:kCAMediaTimingFunctionDefault]];
                [animation setSpeed:0.4];
                [[additionalView  layer] addAnimation:animation forKey:nil];
            }
        }
    }
    else if(recognizer.direction==UISwipeGestureRecognizerDirectionRight)
    {
        if (increment>=0 && increment<[addArray count]) 
        {
            increment--;
            if(increment>[addArray count])
            {
                additionalLabel.text=[[NSString alloc]initWithFormat:@"%@",
                                         [addArray objectAtIndex:increment]];
                flippedLabel.text=[[NSString alloc]initWithFormat:@"%@",
                                      [flippedArray objectAtIndex:increment]];
                NSLog(@"Decrement %d",increment);
                [UIView animateWithDuration:0.55 animations:^{
                    [UIView setAnimationDelay:0.2];
                }];
                CATransition *animation = [CATransition animation];
                [animation setType:kCATransitionPush];
                [animation setSubtype:kCATransitionFromLeft];
                [animation setTimingFunction:[CAMediaTimingFunction 
                               functionWithName:kCAMediaTimingFunctionDefault]];
                [animation setSpeed:0.4];
                [[additionalView layer] addAnimation:animation forKey:nil];
            }
        }
    }
}

仅增量时存在问题。我的 NSLog 打印失败。但我不知道如果手势识别器达到 [addArray count] 的值，如何停止它。

Answer 1

我建议在有效性检查之前增加或减少索引值（您将其命名为增量），如果无效，则在 else 中反转您的操作。像这样：

if (recognizer.direction==UISwipeGestureRecognizerDirectionLeft) 
{
    increment++;

    if (increment<[addArray count]) 
    {
        // Your code
    }
    else
    {
        increment--; // The increment would pass the range of the array, set it back.
    }
}

另一个方向也是如此。

编辑：为了澄清，最初的问题是您检查以确保索引有效，但是，通过在检查后递增，您最终会使其无效。使用您的示例，当增量为 3（数组的最高索引）时，它实际上小于数组的计数，即 4。然后您将索引增加到 4，这将超出范围，或者，在您的案例，落入 if 语句（使用建议将不再需要）并记录您的失败。