BluetoothLeScanner.startScan with Android 5 or later

要多一個 permission

<uses-permission android:name="android.permission.BLUETOOTH" />
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />

LOLLIPOP之後的要使用startScan();

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
    mBluetoothAdapter.startScan();
} else {
    mBluetoothAdapter.startLeScan(mLeScanCallback);
}