水平移動一個UIView

Question

我有2個UIViews（placardView和PlacardView2），我想限制他們時觸摸水平移動但不垂直使用touchesMoved方法。我的想法是讓Y座標等於自己，但是我不能在Xcode中使用語法，因爲我對這類事情很陌生。

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event { 

    UITouch *touch = [touches anyObject]; 

    // If the touch was in the placardView, move the placardView to its location 
    if ([touch view] == placardView) { 
     CGPoint location = [touch locationInView:self]; 
     placardView.center = location; 
     placardView.center.y = placardView.center.y;//error is here 
     return; 
    } 
    if ([touch view] == placardView2) { 
     CGPoint location = [touch locationInView:self]; 
     placardView2.center = location; 
     placardView2.center.y = placardView2.center.y;//error is here 
     return; 
    } 
} 

Answer 1

您不會通過將center.y分配給自己來改變任何東西 - 加上它已經被placardView2.center = location改變了;分配。相反，您應該只分配新的x座標：

CGPoint placardCenter = placardView2.center; 
placardCenter.x = location.x; 
placardView2.center = placardCenter;