WebNov 22, 2024 · drawRect:方法. 每次系统调用drawRect方法之前,都会给drawRect方法传递一个跟当前view相关联上下文(即layer上下文),因此只有在drawRect:方法中才能获 … Web4、改变view的size会触发父view的layoutSubviews 5、滚动会触发layoutSubviews 6、旋转Screen会触发父UIView上的layoutSubviews事件. 二、什么情况会调用draw rect方法. 1、controller的loadView、viewdidLoad方法调用之后,view即将出现在屏幕之前系统调用drawRect。 2、sizeToFit方法调用之后。
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WebOct 9, 2016 · drawRect方法使用注意事项:drawRect在以下情况下会被调用: 1、如果在UIView初始化时没有设置rect大小,将直接导致drawRect不被自动调用。 drawRect 掉 … WebApr 8, 2009 · Note specifically that is why layoutSubviews: is called whenever a UIScrollView scrolls, as it performs the scrolling by changing its bounds' origin. Changing the frame will only change the bounds if the size has changed, as this is the only thing propagated to the bounds property. A change in bounds of a view that is not yet in a view ... product to remove scratches from car
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WebJan 8, 2024 · layoutSubviews 调用时机. 一般baidu出来的答案如下,然而说明并不够透彻,在此补充说明: 1、init初始化不会触发layoutSubviews. 2、addSubview会触发layoutSubviews. 3、设置view的Frame会触发layoutSubviews,当然前提是frame的值设置前后发生了变化. 4、滚动一个UIScrollView会触发 ... Web1.5、View的 frame 发生变化时,会调用父控件的LayoutSubViews. 1.6、父控件的frame发生变化时,会调用View的layoutSubViews. 1.7、滚动一个UIScrollView会触发View的layoutSubviews. 1.8、旋转Screen会触发父控件的layoutSubviews事件(控制器的ViewWillLayoutSubView) drawRect. 重写此方法,执行重绘 ... WebDraws the outline of the specified rectangle. The left and right edges of the rectangle are at x and x + width.The top and bottom edges are at y and y + height.The rectangle is drawn using the graphics context's current color. product to remove scratches from appliances