生成服务器端推送p12文件
所需文件：A、开发证书 aps_production.cer
B、本地导出的私钥 ： aps_production.p12
C、生成证书时用到的请求文件：Push.certSigningRequest
1、将aps_production.cer转换成aps_production_identity.pem格式
openssl x509 -in aps_production.cer -inform DER -out aps_production_identity.pem -outform PEM
2、将本地私有p12格式的私钥转换成pem
openssl pkcs12 -nocerts -out apple_push_notification_production.pem -in aps_production.p12
3、创建服务器p12文件（aps_production_identity.p12）
openssl pkcs12 -export -in aps_production_identity.pem -inkey apple_push_notification_production.pem -certfile Push.certSigningRequest -name "aps_production_identity" -out aps_production_identity.p12
