UIPopoverController的定位

在UIPopoverController中提供了两种方法来指向按钮，分别是presentPopoverFromRect: inView: permittedArrowDirections: animated:和presentPopoverFromBarButtonItem: permittedArrowDirections: animated:，第二种方法好说，不用考虑位置。但是，当我们要指向视图中的某个按钮时，就要使用第一个方法了。而这个方法的难点就是，怎么准确的将箭头指向按钮。这个箭头的指向坐标是靠presentPopoverFromRect:这个参数来决定的。

 

UIImagePickerController *imagePicker = [[UIImagePickerController alloc] init];
if ([UIImagePickerController isSourceTypeAvailable:
		 UIImagePickerControllerSourceTypePhotoLibrary]) {		
	imagePicker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
	imagePicker.delegate = self;
	[imagePicker setAllowsEditing:NO];
	UIPopoverController *popover = [[UIPopoverController alloc] initWithContentViewController:imagePicker];
	self.popoverController = popover;
	[popoverController presentPopoverFromRect:CGRectMake(385, 500, 70, 35) inView:self.view permittedArrowDirections:UIPopoverArrowDirectionRight animated:YES];
	[popover release];
	[imagePicker release];
}

 

这段代码执行后的效果图：

 

那么，CGRectMake(385, 500, 70, 35)是视图中的哪个区域呢？看下图，你就清楚了：