Android v/s ios (In Terms of Security and Privacy)

Security:

Android’s applications are isolated from the rest of the system’s resources, unless a user specifically grants an application access to other features. This makes the system less vulnerable to bugs, but developer confusion means that many apps ask for unnecessary permissions. The most widespread malware on Android is one where text messages are sent to premium rate numbers without the knowledge of the user, and the sending of personal information to unauthorized third parties. As it is the more popular smartphone operating system, it is more likely to be the focus of attacks.

Malware writers are less likely to write apps for iOS, due to Apple's review of all the apps and verification of the identity of app publishers. However, if an iOS device is jailbroken and apps installed from outside Apple's store, it can be vulnerable to attacks and malware.

Privacy:

When it comes to protecting users' private information, iOS wins. When installing apps on Android, the user is presented with all the permissions that the app is requesting. This is an all-or-nothing proposition. The user can choose to accept the app's request for permissions or not install the app at all. App developers take advantage of this "feature" and request a lot of user information. For example, Pandora's mobile app on Android requests permissions for your Google identity, contacts, calendar, photos, media, files and even call information.

Pandora's app on iOS gets no such permissions. After it is installed and opened by the user, an iOS app may request additional permissions like location and access to Contacts. But the user can reject these permission requests. Even after approving the permission requests, iOS users can quickly glance at which apps have access to their Contacts and location data, and turn off access for apps with which they no longer want to share this data.

In November 2014, Twitter announced that it is now tracking the list of apps its users have installed on their phones. Both iOS and Android are vulnerable — an app installed on either platform can get a list of other apps installed on the same device.