iOS 9 之前，检测外接键盘连接的最可靠方法是监听 UIKeyboardWillShowNotification 并将文本字段设置为第一响应者，如此问题所述。虚拟键盘时，通知会被触发，但使用外接键盘时不会触发。
然而，随着 iOS 9 的到来，这种行为已经改变了。由于现在会显示新的键盘工具栏，因此连接外接键盘时也会触发 UIKeyboardWillShowNotification。
仍然可以检测键盘高度并判断显示的是较小的工具栏还是较大的虚拟键盘。但是，由于键盘高度在各个测试版之间已经发生了变化，所以这种方法不可靠，并且不能保证随时间而保持不变。
是否有更可靠的方法可用于 iOS 9？
回到原问题后，我找到了一个可行的解决方案。
似乎当常规虚拟键盘显示时，键盘框架位于屏幕尺寸内。但是，当连接一个物理键盘并显示键盘工具栏时，键盘框架会位于屏幕外。我们可以检查键盘框架是否位于屏幕外来确定键盘工具栏是否显示。
Objective-C
- (void) keyboardWillShow:(NSNotification *)notification {
NSDictionary* userInfo = [notification userInfo];
CGRect keyboardFrame = [[userInfo objectForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue];
CGRect keyboard = [self.view convertRect:keyboardFrame fromView:self.view.window];
CGFloat height = self.view.frame.size.height;
if ((keyboard.origin.y + keyboard.size.height) > height) {
self.hasKeyboard = YES;
}
}
Swift
@objc func keyboardWillShow(_ notification: NSNotification) {
guard let userInfo = notification.userInfo else {return}
let keyboardScreenEndFrame = (userInfo[UIResponder.keyboardFrameEndUserInfoKey] as! NSValue).cgRectValue
let keyboard = self.view.convert(keyboardScreenEndFrame, from: self.view.window)
let height = self.view.frame.size.height
if (keyboard.origin.y + keyboard.size.height) > height {
self.hasKeyboard = true
}
}
CGFloat toolbarHeight = height - keyboard.origin.y - SoftDesignerkeyboard.origin.y + keyboard.size.height的值等于self.view.frame.size.height。然而，我发现在所有情况下keyboard.size.height都等于55。 - ɯɐɹʞself.hasKeyboard = (keyboard.origin.y + keyboard.size.height) > height以确保在外部键盘被移除时，它会被设置回false。 - chrysbiOS 14 的 SDK 终于为此提供了公共 API：GCKeyboard。要检查外部键盘是否已连接：
let isKeyboardConnected = GCKeyboard.coalesced != nil
注意：
import GameController 导入游戏控制器模块if #available(iOS 14.0, *) 中这段代码支持iOS 8和iOS 9，使用inputAccessoryView，有双重保护常量以准备未来iOS版本的新更改并支持新设备:
#define gThresholdForHardwareKeyboardToolbar 160.f // it's minimum height of the software keyboard on non-retina iPhone in landscape mode
- (bool)isHardwareKeyboardUsed:(NSNotification*)keyboardNotification {
NSDictionary* info = [keyboardNotification userInfo];
CGRect keyboardEndFrame;
[[info valueForKey:UIKeyboardFrameEndUserInfoKey] getValue:&keyboardEndFrame];
float height = [[UIScreen mainScreen] bounds].size.height - keyboardEndFrame.origin.y;
return height < gThresholdForHardwareKeyboardToolbar;
}
我正在使用Sarah Elan的答案的变体。在某些视图中，我对她的方法有问题。我从未完全弄清楚是什么导致了问题。但这里有另一种方法来确定您是否拥有ios9外部键盘“撤消”栏，而不是全尺寸键盘。
它可能不太向前兼容，因为如果他们更改撤消栏的大小，这会破坏它。但是，它完成了工作。我欢迎批评，因为一定有更好的方法......
//... somewhere ...
#define HARDWARE_KEYBOARD_SIZE_IOS9 55
//
+ (BOOL) isExternalKeyboard:(NSNotification*)keyboardNotification {
NSDictionary* info = [keyboardNotification userInfo];
CGRect keyboardEndFrame;
[[info valueForKey:UIKeyboardFrameEndUserInfoKey] getValue:&keyboardEndFrame];
CGRect keyboardBeginFrame;
[[info valueForKey:UIKeyboardFrameBeginUserInfoKey] getValue:&keyboardBeginFrame];
CGFloat diff = keyboardEndFrame.origin.y - keyboardBeginFrame.origin.y;
return fabs(diff) == HARDWARE_KEYBOARD_SIZE_IOS9;
}
CGFloat toolbarHeight = UIScreen.mainScreen().bounds.height - keyboardEndFrame.origin.y - SoftDesignerCGRect kbEndFrame = [[[notification userInfo] objectForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue];
两个都具有值为0的价值
因此，您可以通过以下方式检测外部硬件:
if(kbEndFrame.size.height == 0)
// External/virtual KB exists
else
// Virtual on screen KB exists
#import "UIKit/UIKeyboardImpl.h"
+ (BOOL)isHardwareKeyboardMode
{
UIKeyboardImpl *kbi = [UIKeyboardImpl sharedInstance];
BOOL externalKeyboard = kbi.inHardwareKeyboardMode;
NSLog(@"Using external keyboard? %@", externalKeyboard?@"YES":@"NO");
return externalKeyboard;
}
[UIKeyboardImpl sharedInstance] 抛出异常。 - kambala这个解决方案适用于iOS 9 - iOS 16（仅限iPhone，不适用于最新的iPad）
class ViewController: UIViewController {
// declare a proprty where you will store keyboard notifications
private var cachedKeyboardNotification: Notification?
// in this iexample tere is only one text fiels which can trigger the keyboard
var textField: UItextField!
override func viewDidLoad() {
NotificationCenter.default.addObserver(self, selector: #selector(keyboardNotifications), name: UIWindow.keyboardDidShowNotification, object: nil)
NotificationCenter.default.addObserver(self, selector: #selector(keyboardNotifications), name: UIWindow.keyboardDidChangeFrameNotification, object: nil)
}
// store the keyboard notifioaction
@objc func keyboardNotifications(_ notification: Notification) {
cachedKeyboardNotification = notification
}
func isKeyboardExternal() -> Bool {
guard let notification = cachedKeyboardNotification else {
return false
}
guard let kbEndFrame = (notification.userInfo?[UIWindow.keyboardFrameEndUserInfoKey] as? NSValue)?.cgRectValue else {
return false
}
let offset = kbEndFrame.maxY - UIScreen.main.bounds.height
let kbVisibleHeight = kbEndFrame.height - offset
let accessoryViewHeight = textField.inputAccessoryView?.frame.height ?? 0
return kbVisibleHeight - accessoryViewHeight == 0
}
....
}
你可以尝试使用Core Bluetooth检查正在广播服务的外围设备。
CBCentralManager *centralManager = [[CBCentralManager alloc] initWithDelegate:self queue:nil];
[centralManager scanForPeripheralsWithServices:nil options:nil];
你应该实现代理：
- (void)centralManager:(CBCentralManager * _Nonnull)central
didDiscoverPeripheral:(CBPeripheral * _Nonnull)peripheral
advertisementData:(NSDictionary<NSString *,
id> * _Nonnull)advertisementData
RSSI:(NSNumber * _Nonnull)RSSI{
}
GCKeyboard框架来确定是否插入了键盘。我现在需要这个功能，所以很快就会尝试一下。 - David H如果您使工具栏变得无关紧要，则键盘不会显示。在iOS 12.4上，通过清空其左右组来实现此目的：
textField.inputAssistantItem.leadingBarButtonGroups = []
textField.inputAssistantItem.trailingBarButtonGroups = []
...如果有帮助的话，这里是一种快速观察的方法：
// Watch for a soft keyboard to show up
let observer = NotificationCenter.default.addObserver(forName: UIWindow.keyboardWillShowNotification, object: nil, queue: nil) { notification in
print("no external keyboard")
}
// Stop observing shortly after, since the keyboard should have shown by now
DispatchQueue.main.asyncAfter(deadline: .now() + 0.5) {
NotificationCenter.default.removeObserver(observer)
}
当外部设备连接时，您可以订阅通知：
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(deviceConnected:) name:EAAccessoryDidConnectNotification object:nil];
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(deviceDisconnected:) name:EAAccessoryDidDisconnectNotification object:nil];
[[EAAccessoryManager sharedAccessoryManager] registerForLocalNotifications];
或者只需检索附加设备列表：
EAAccessoryManager* accessoryManager = [EAAccessoryManager sharedAccessoryManager];
if (accessoryManager)
{
NSArray* connectedAccessories = [accessoryManager connectedAccessories];
NSLog(@"ConnectedAccessories = %@", connectedAccessories);
}