iphone開發 - UIRotationGestureRecognizer（順時針和逆時針檢測）？

Question

有沒有辦法檢測用戶所做的旋轉是順時針還是逆時針直接？

我搜索了，但無法找到答案！

我的代碼如下所示：

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

Answer 1

的rotation屬性會告訴你在弧度rotation。負值表示旋轉是順時針的，正值表示逆時針旋轉。

例子：

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 
    } 
}