How to connect Android device to an iOS device over BLE (Bluetooth Low Energy)

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Adding a summary for reference:

What could it be? There are some limitations on Android or iOS that don’t permit to connect from an Android to an iOS or viceversa?

When connecting to a GATT server that is advertised as dualmode (BLE and BR/EDR) device by calling connectGatt(…), the TRANSPORT_AUTO flag that is internally added makes Android to default to the BR/EDR mode (link).

Following workarounds are possible:

  1. Peripheral side: Stop advertising BR/EDR capabilities by adjusting
    the appropriate flags (link)
  2. Central side: Set the transport parameter explicitely to
    TRANSPORT_LE by calling the hidden version of connectGatt() using
    reflection

Example:

public void connectToGatt(BluetoothDevice device) {    
   ...    
   Method m = device.getClass().getDeclaredMethod("connectGatt", Context.class, boolean.class, BluetoothGattCallback.class, int.class);    
   int transport = device.getClass().getDeclaredField("TRANSPORT_LE").getInt(null);     // LE = 2, BREDR = 1, AUTO = 0    
   BluetoothGatt mGatt = (BluetoothGatt) m.invoke(device, this, false, gattCallback, transport);    
   ... 
}

Edit 4/2016

As Arbel Israeli pointed out in the comment, Google introduced an overloaded version of connectGatt(…) which allows to specify the transport in Android M.

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