有没有一种API可以确定Apple Pencil是否连接到iPad Pro? 查看9.1 SDK,我没有发现直接实现此功能的内容。或者,也许可以使用蓝牙API来完成。
有没有一种API可以确定Apple Pencil是否连接到iPad Pro? 查看9.1 SDK,我没有发现直接实现此功能的内容。或者,也许可以使用蓝牙API来完成。
我找不到任何关于Apple Pencil的蓝牙实现的实际文档(我认为也不存在),但是以下代码可以正常工作。
它检查广告支持“设备信息”服务的连接设备,然后检查其中是否有名称为“Apple Pencil”的设备。
@import CoreBluetooth
@interface PencilDetector : NSObject <CBCentralManagerDelegate>
- (instancetype)init;
@end
#include "PencilDetector.h"
@interface PencilDetector ()
@end
@implementation PencilDetector
{
CBCentralManager* m_centralManager;
}
- (instancetype)init
{
self = [super init];
if (self != nil) {
// Save a reference to the central manager. Without doing this, we never get
// the call to centralManagerDidUpdateState method.
m_centralManager = [[CBCentralManager alloc] initWithDelegate:self
queue:nil
options:nil];
}
return self;
}
- (void)centralManagerDidUpdateState:(CBCentralManager *)central
{
if ([central state] == CBCentralManagerStatePoweredOn)
{
// Device information UUID
NSArray* myArray = [NSArray arrayWithObject:[CBUUID UUIDWithString:@"180A"]];
NSArray* peripherals =
[m_centralManager retrieveConnectedPeripheralsWithServices:myArray];
for (CBPeripheral* peripheral in peripherals)
{
if ([[peripheral name] isEqualToString:@"Apple Pencil"])
{
// The Apple pencil is connected
}
}
}
}
@end
CBCentralManagerStatePoweredOn
之前,不应调用管理器上的任何方法,因此较长的代码可能更安全。
m_centralManager = [[CBCentralManager alloc] initWithDelegate:nil
queue:nil
options:nil];
// Device information UUID
NSArray* myArray = [NSArray arrayWithObject:[CBUUID UUIDWithString:@"180A"]];
NSArray* peripherals =
[m_centralManager retrieveConnectedPeripheralsWithServices:myArray];
for (CBPeripheral* peripheral in peripherals)
{
if ([[peripheral name] isEqualToString:@"Apple Pencil"])
{
// The Apple pencil is connected
}
}
0x180A
,这是蓝牙“分配号码”或“短UUID”用于“设备信息”服务。这是当前Pencil设备提供的一项服务,并且随着大多数(或可能所有)蓝牙设备都应该提供此服务,它应该会在未来继续工作。 - Richconnect(_ peripheral: CBPeripheral, options: [String : Any]? = nil)
函数初始化连接时,CBCentralManager的centralManager(_ central: CBCentralManager, didConnect peripheral: CBPeripheral)
才会被调用(是的,阅读文档有所帮助:])。ApplePencilReachability
时,设置一个定时器以每秒检查pencil的可用性。如果找到笔,则定时器将被无效化;如果关闭蓝牙,则也将被无效化。重新打开后会创建一个新的计时器。import CoreBluetooth
class ApplePencilReachability: NSObject, CBCentralManagerDelegate {
private let centralManager = CBCentralManager()
var pencilAvailabilityDidChangeClosure: ((_ isAvailable: Bool) -> Void)?
var timer: Timer? {
didSet {
if oldValue !== timer { oldValue?.invalidate() }
}
}
var isPencilAvailable = false {
didSet {
guard oldValue != isPencilAvailable else { return }
pencilAvailabilityDidChangeClosure?(isPencilAvailable)
}
}
override init() {
super.init()
centralManager.delegate = self
centralManagerDidUpdateState(centralManager) // can be powered-on already?
}
deinit { timer?.invalidate() }
func centralManagerDidUpdateState(_ central: CBCentralManager) {
if central.state == .poweredOn {
timer = Timer.scheduledTimer(withTimeInterval: 1, repeats: true) {
[weak self] timer in // break retain-cycle
self?.checkAvailability()
if self == nil { timer.invalidate() }
}
} else {
timer = nil
isPencilAvailable = false
}
}
private func checkAvailability() {
let peripherals = centralManager.retrieveConnectedPeripherals(withServices: [CBUUID(string: "180A")])
let oldPencilAvailability = isPencilAvailable
isPencilAvailable = peripherals.contains(where: { $0.name == "Apple Pencil" })
if isPencilAvailable {
timer = nil // only if you want to stop once detected
}
}
}
CBCentralManager.registerForConnectionEvents
方法,因此不需要像这样每秒轮询。 - Matt Gallagher