ios - 为 UISwipeGestureRecognizer 设置方向

Question

我想向基于 View 的 iPhone 项目添加简单的滑动手势识别。应识别所有方向(右、下、左、上)的手势。

在 UISwipeGestureRecognizer 的文档中有说明:

You may specify multiple directions by specifying multiple UISwipeGestureRecognizerDirection constants using bitwise-OR operands. The default direction is UISwipeGestureRecognizerDirectionRight.

但是对我来说它不起作用。当所有四个方向都进行“或”运算时，仅识别左右滑动。

- (void)viewDidLoad {
    UISwipeGestureRecognizer *recognizer;

    recognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleSwipeFrom:)];
    [recognizer setDirection:(UISwipeGestureRecognizerDirectionRight | UISwipeGestureRecognizerDirectionDown | UISwipeGestureRecognizerDirectionLeft | UISwipeGestureRecognizerDirectionUp)];
    [[self view] addGestureRecognizer:recognizer];
    [recognizer release]; 
    [super viewDidLoad];
}

-(void)handleSwipeFrom:(UISwipeGestureRecognizer *)recognizer {
    NSLog(@"Swipe received.");
}

我通过向 View 添加四个识别器来修复此问题，但我很想知道为什么它没有像文档中宣传的那样工作？

- (void)viewDidLoad {
    UISwipeGestureRecognizer *recognizer;

    recognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleSwipeFrom:)];
    [recognizer setDirection:(UISwipeGestureRecognizerDirectionRight)];
    [[self view] addGestureRecognizer:recognizer];
    [recognizer release];

    recognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleSwipeFrom:)];
    [recognizer setDirection:(UISwipeGestureRecognizerDirectionUp)];
    [[self view] addGestureRecognizer:recognizer];
    [recognizer release];

    recognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleSwipeFrom:)];
    [recognizer setDirection:(UISwipeGestureRecognizerDirectionDown)];
    [[self view] addGestureRecognizer:recognizer];
    [recognizer release];

    recognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(handleSwipeFrom:)];
    [recognizer setDirection:(UISwipeGestureRecognizerDirectionLeft)];
    [[self view] addGestureRecognizer:recognizer];
    [recognizer release];

    [super viewDidLoad];
}

-(void)handleSwipeFrom:(UISwipeGestureRecognizer *)recognizer {
    NSLog(@"Swipe received.");
}

Answer 1

似乎有一个错误。您可以像以前一样指定允许的方向。但是，当您尝试访问触发操作选择器方法中的滑动的实际方向时，您仍然会得到您最初设置的位掩码(对于允许的方向)。

这意味着当允许超过 1 个方向时，对实际方向的检查将始终失败。 当您在选择器方法(即 -(void)scrollViewSwiped:(UISwipeGestureRecognizer *)recognizer)中输出“方向”的值时，您可以很容易地自己看到它。

向 Apple 提交错误报告 (#8276386)。

[更新] 我得到了 Apple 的答复，说该行为按预期工作。

例如，在表格 View 中，您可以在表格 View 单元格中向左或向右滑动以触发“删除”(这会将滑动手势的方向设置为向左和向右)

这意味着原来的解决方法是它应该使用的方式。 direction 属性只能用于正确识别手势，但不能在成功识别时执行的方法中比较触发识别的实际方向。