ios-php do APNs need to do what several documents?

iOS developers say that only a suffix named P12 is available.

After I converted this p12 to PEM and wrote a send test with PHP, I was prompted:

Unable to Connect:tls://gateway.push.apple.com:2195:2
(Stream_socket_client (): Failed to enable crypto)

I see that there is a need for a certificate and a private key text, that is, two files, but some of the information did not say so, so do not understand exactly what documents are required.

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iOS developers say that only a suffix named P12 is available.

After I converted this p12 to PEM and wrote a send test with PHP, I was prompted:

Unable to Connect:tls://gateway.push.apple.com:2195:2
(Stream_socket_client (): Failed to enable crypto)

I see that there is a need for a certificate and a private key text, that is, two files, but some of the information did not say so, so do not understand exactly what documents are required.

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