我在一个多星期前提交了应用，今天收到了可怕的拒绝邮件。它告诉我，我的应用程序不能被接受，因为我使用的是非公共API;具体来说，它说，
应用程序中包含的非公共API是firstResponder。
现在，违规的API调用实际上是一个解决方案，我发现这里的SO:
UIWindow *keyWindow = [[UIApplication sharedApplication] keyWindow];
UIView *firstResponder = [keyWindow performSelector:@selector(firstResponder)];
如何在屏幕上显示当前的第一响应器?我正在寻找一种不会让我的应用程序被拒绝的方法。
当前回答
Peter Steinberger刚刚发了关于私有通知UIWindowFirstResponderDidChangeNotification的推特，如果你想观察firstResponder的变化，你可以观察。
其他回答
这是递归的一个很好的候选!不需要添加一个类别到UIView。
用法(来自你的视图控制器):
UIView *firstResponder = [self findFirstResponder:[self view]];
代码:
// This is a recursive function
- (UIView *)findFirstResponder:(UIView *)view {
if ([view isFirstResponder]) return view; // Base case
for (UIView *subView in [view subviews]) {
if ([self findFirstResponder:subView]) return subView; // Recursion
}
return nil;
}
这里是Jakob Egger方法的Swift版本:
import UIKit
private weak var currentFirstResponder: UIResponder?
extension UIResponder {
static func firstResponder() -> UIResponder? {
currentFirstResponder = nil
UIApplication.sharedApplication().sendAction(#selector(self.findFirstResponder(_:)), to: nil, from: nil, forEvent: nil)
return currentFirstResponder
}
func findFirstResponder(sender: AnyObject) {
currentFirstResponder = self
}
}
对于Swift 3和4版本的nevyn的回答:
UIApplication.shared.sendAction(#selector(UIView.resignFirstResponder), to: nil, from: nil, for: nil)
下面是一个基于Jakob Egger最优秀的答案在Swift中实现的扩展:
import UIKit
extension UIResponder {
// Swift 1.2 finally supports static vars!. If you use 1.1 see:
// http://stackoverflow.com/a/24924535/385979
private weak static var _currentFirstResponder: UIResponder? = nil
public class func currentFirstResponder() -> UIResponder? {
UIResponder._currentFirstResponder = nil
UIApplication.sharedApplication().sendAction("findFirstResponder:", to: nil, from: nil, forEvent: nil)
return UIResponder._currentFirstResponder
}
internal func findFirstResponder(sender: AnyObject) {
UIResponder._currentFirstResponder = self
}
}
斯威夫特4
import UIKit
extension UIResponder {
private weak static var _currentFirstResponder: UIResponder? = nil
public static var current: UIResponder? {
UIResponder._currentFirstResponder = nil
UIApplication.shared.sendAction(#selector(findFirstResponder(sender:)), to: nil, from: nil, for: nil)
return UIResponder._currentFirstResponder
}
@objc internal func findFirstResponder(sender: AnyObject) {
UIResponder._currentFirstResponder = self
}
}
你可以选择下面的UIView扩展来获得它(credit by Daniel):
extension UIView {
var firstResponder: UIView? {
guard !isFirstResponder else { return self }
return subviews.first(where: {$0.firstResponder != nil })
}
}
