Apple 缺少有关如何使用 iOS5 中引入的 UIPopoverBackgroundView 类的文档.谁有例子?
Apple is missing documentation on how to use UIPopoverBackgroundView class introduced in iOS5. Anyone have an example?
我尝试将其子类化，但我在 Lion 上的 XCode 4.2 缺少 UIPopoverBackgroundView.h
I have tried to subclass it, but my XCode 4.2 on Lion is missing UIPopoverBackgroundView.h
不出所料，它应该被导入为 #import <UIKit/UIPopoverBackgroundView.h>
要添加到其他仅链接的答案，这是如何完成的.
To add to the other, link-only answers, here is how this is done.
在您的界面中声明以下内容:
Declare the following in your interface:
+(UIEdgeInsets)contentViewInsets;
+(CGFloat)arrowHeight;
+(CGFloat)arrowBase;
@property(nonatomic,readwrite) CGFloat arrowOffset;
@property(nonatomic,readwrite) UIPopoverArrowDirection arrowDirection;
类方法很简单:contentViewInsets返回你的边框的宽度(不包括箭头)，arrowHeight是你的高度箭头，arrowBase 是箭头的基础.
The class methods are straightforward: contentViewInsets returns the width of your borders all the way round (not including the arrow), arrowHeight is the height of your arrow, arrowBase is the base of your arrow.
self.bounds，在箭头所在的边缘由 arrowHeight 插入self中心arrowOffset(根据轴正确).如果箭头方向不向上，您必须更改图像方向，但我的弹出框只会向上，所以我没有这样做.self.bounds, inset by arrowHeight on whatever edge the arrow is onarrowOffset away from the centre of self (correct according to the axis). You have to change the image orientation if the arrow direction is not up, but my popover would only be up so I didn't do that.这是我的 Up-only 子类的 layoutSubviews 方法:
Here is the layoutSubviews method for my Up-only subclass:
-(void)layoutSubviews
{
if (self.arrowDirection == UIPopoverArrowDirectionUp)
{
CGFloat height = [[self class] arrowHeight];
CGFloat base = [[self class] arrowBase];
self.background.frame = CGRectMake(0, height, self.frame.size.width, self.frame.size.height - height);
self.arrow.frame = CGRectMake(self.frame.size.width * 0.5 + self.arrowOffset - base * 0.5, 1.0, base, height);
[self bringSubviewToFront:self.arrow];
}
}
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