我想根据内容动态设置 Collection View 的高度，我尝试了以下代码:
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(true)
self.ItemCollection.addObserver(self , forKeyPath: "contentSize", options: NSKeyValueObservingOptions.old, context: nil)
}
func observeValueForKeyPath(keyPath: String?, ofObject object: AnyObject?, change: [String : AnyObject]?, context: UnsafeMutableRawPointer) {
let newHeight : CGFloat = self.ItemCollection.collectionViewLayout.collectionViewContentSize.height
var frame : CGRect! = self.ItemCollection.frame
frame.size.height = newHeight
self.ItemCollection.frame = frame
}
override func viewWillDisappear(_ animated: Bool) {
super.viewWillDisappear(true)
self.ItemCollection.removeObserver(self, forKeyPath: "contentSize")
}
我在这一行遇到错误:
self.ItemCollection.addObserver(self , forKeyPath: "contentSize", options: NSKeyValueObservingOptions.old, context: nil)
错误如下:
An -observeValueForKeyPath:ofObject:change:context: message was received but not handled.
Key path: contentSize
Observed object: <UICollectionView: 0x102911200; frame = (0 275; 375 360); clipsToBounds = YES; autoresize = W+TM+H+BM; gestureRecognizers = <NSArray: 0x1c4247a40>; layer = <CALayer: 0x1c02388a0>; contentOffset: {0, 0}; contentSize: {375, 0}; adjustedContentInset: {0, 0, 0, 0}> collection view layout: <UICollectionViewFlowLayout: 0x102543a80>
Change: {
kind = 1;
old = "NSSize: {20, 360}";
}
Context: 0x0'
最佳答案
在 Swift 4 中，它是一个覆盖函数，应该是 -
override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?)
关于ios - 错误 : An -observeValueForKeyPath:ofObject:change:context: message was received but not handled，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/47150577/