Log on to the Apple Developer Portal, and click Member Center.

The Developer Program Resources page appears.

The Certificates, Identifiers & Profiles page appears.

Under iOS Apps, select Certificates.

The iOS Apps appears in the left pane and iOS Certificates appears in the right pane.

In the left pane, click Certificates.

A list of all of the certificates that you created appears.

To create a new certificate, click Add (+) button.

On the Select Type tab, select iOS App Development for Development Certificate, and then click Continue.

On the Request tab, click Continue. The Generate tab appears.

In your Mac system, in Applications, under Utilities, open Keychain Access.

On the Quick Access bar, select Keychain Access, point to Certificate Assistant, select Request a Certificate From a Certificate Authority, and then click Save.

The Certificate Information wizard appears.

In the Certificate Information wizard, type the appropriate values in the User Email Address, Common Name, CA Email Address fields.

Click the Saved to disk option to save the Certificate Signing Request (Request) on your system, and click Continue.

A page displaying the default location of the request appears.

Browse and select the location where you want to save the Certificate Signing Request, and click Save.

The Conclusion page appears.

(Optional) To verify if the Request file has been successfully generated, click Show in folder….

The folder that contains the request appears.

Click Done.

In the Apple Developer Portal, on the Generate tab, click Choose File…, and select the CSR file that you have created using Keychain Access.

Click Generate.

A message notifying that your certificate is pending issuance appears.

After the certificate is issued, click Download to save the certificate onto your system.

The Development Certificate is generated and saved on your system.