Firebase pod install - pod 'Firebase/Database' - Required a higher minimum deployment target

This is how I fixed it.

Step 1

Install Regular Firebase - pod 'Firebase', '>= 2.5.1'

Step 2

Update - pod update

*At this point it will take a good couple minutes to update. You should see something like this.

Update all pods
Updating local specs repositories
Analyzing dependencies
Downloading dependencies
Installing Firebase 3.2.0 (was 3.2.0)
Using FirebaseAnalytics (3.2.0)
Installing FirebaseAuth (3.0.2)
Using FirebaseDatabase (3.0.1)
Using FirebaseInstanceID (1.0.6)
Using GoogleInterchangeUtilities (1.2.1)
Installing GoogleNetworkingUtilities (1.2.1)
Using GoogleSymbolUtilities (1.1.1)
Using GoogleUtilities (1.3.1)
Generating Pods project
Integrating client project
Sending stats
Pod installation complete! There are 4 dependencies from the Podfile and 10
total pods installed.

Step 3

Now you should have Firebase 3. So you can add frameworks like such in your pod file then pod update

# Uncomment this line to define a global platform for your project
 platform :ios, '8.0'
# Uncomment this line if you're using Swift
 use_frameworks!

target 'xMarket' do

end

target 'xMarketTests' do

end

target 'xMarketUITests' do

end

pod 'Firebase', '>= 2.5.1'
pod ‘Firebase/Core’
pod ‘Firebase/Database’
pod ‘Firebase/Auth’

Good luck!

In your Podfile, change the line pod 'Firebase' to pod Firebase/Core and run pod update in the project folder.

With the new Firebase, there is no need for the first line.

From the migration guide:

Reference: Firebase.google migration guide