iphone开发-UItapGestureRecognizer(顺时针或逆时针检测)？

Question

有没有办法检测用户所做的旋转是顺时针还是逆时针方向？？？

我搜索过但找不到答案!

我的代码如下所示:

 UIGestureRecognizer *recognizer;
 recognizer = [[UIRotationGestureRecognizer alloc] initWithTarget:self action:@selector(spin)];
 [self.rotating addGestureRecognizer:recognizer];
 [recognizer release];

Answer 1

rotation 属性会告诉您 rotation以弧度为单位。负值表示顺时针旋转，正值表示逆时针旋转。

示例:

UIGestureRecognizer *recognizer;
recognizer = [[UIRotationGestureRecognizer alloc] initWithTarget:self action:@selector(spin:)];  // <-- Note the colon after the method name
[self.rotating addGestureRecognizer:recognizer];
[recognizer release];

- (void)spin:(UIGestureRecognizer *)gestureRecognizer {
    CGFloat rotation = gestureRecognizer.rotation;
    if (rotation < 0) {
        // clockwise
    } else {
        // counter-clockwise
    }
}