Why Does iOS 6 Safari Cache My $.ajax Calls Even With `no-cache` Headers?

iOS 6 Safari: Caching $.ajax Calls

Safari's web view in iOS 6 has been observed to cache $.ajax calls, even when explicitly specified not to. This peculiar behavior has been encountered in the context of PhoneGap applications, which utilize the Safari WebView.

Cause of Caching Issue

Investigation has revealed that Safari caches POST requests that lack Cache-Control headers or contain the header "Cache-Control: max-age=0." This behavior stems from an interpretation of the HTTP spec, which states that POST responses can be cached with appropriate headers.

Solutions

To prevent caching, the Cache-Control header should be set to "no-cache." This can be achieved globally in Apache configurations using:

Header set Cache-Control "no-cache"

For POST requests specifically, the same setting can be applied using:

SetEnvIf Request_Method "POST" IS_POST
Header set Cache-Control "no-cache" env=IS_POST

Alternatively, a workaround is to modify function signatures:

getNewRecordID(intRecordType, strTimestamp)

By adding a timestamp parameter to the function signature, the request effectively changes with each call, preventing caching.

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