哪里可以找到有关iOS 8可变触摸尺寸API的信息

Question

根据MacRumor(http://www.macrumors.com/2014/06/17/pencil-stylus-pressure-ios-8/),iOS 8将支持模拟表面压力的可变触摸尺寸.我在哪里可以找到它的API？我搜索了Apple Developer iOS开发中心在线图书馆,但找不到它.

Answer 1

iOS 8在UITouch上添加了两个新属性:majorRadius和majorRadiusTolerance.他们的工作方式如下:

override func touchesMoved(touches: NSSet!, withEvent event: UIEvent!) {
    var touch : UITouch = touches.anyObject() as UITouch
    var lowerBound = touch.majorRadius - touch.majorRadiusTolerance
    var upperBound = touch.majorRadius + touch.majorRadiusTolerance
    var average = (lowerBound + upperBound) / 2.0
    println("touch was between \(lowerBound)pt and \(upperBound)pt in size (avg \(average)")
}

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