patch for FFmpeg cache on iOS

patch.diff

diff --git a/libavutil/file_open.c b/libavutil/file_open.c
index 34070d933b..f96bdf11ac 100644
--- a/libavutil/file_open.c
+++ b/libavutil/file_open.c
@@ -28,6 +28,9 @@
 #if HAVE_IO_H
 #include <io.h>
 #endif
+#if defined(__APPLE__)
+#include <CoreFoundation/CoreFoundation.h>
+#endif
 
 #if defined(_WIN32) && !defined(__MINGW32CE__)
 #undef open
@@ -116,6 +119,9 @@ int avpriv_tempfile(const char *prefix, char **filename, int log_offset, void *l
     free(ptr);
 #else
     size_t len = strlen(prefix) + 12; /* room for "/tmp/" and "XXXXXX\0" */
+#if defined(__APPLE__)
+    len = PATH_MAX;
+#endif
     *filename  = av_malloc(len);
 #endif
     /* -----common section-----*/
@@ -140,6 +146,17 @@ int avpriv_tempfile(const char *prefix, char **filename, int log_offset, void *l
         fd = mkstemp(*filename);
     }
 #endif
+#if defined(__APPLE__)
+    if (fd < 0) {
+        CFURLRef homeUrl = CFCopyHomeDirectoryURL();
+        char homeStr[PATH_MAX];
+        bzero(homeStr,PATH_MAX);
+        CFURLGetFileSystemRepresentation(homeUrl, false, homeStr, PATH_MAX);
+
+        snprintf(*filename, len, "%s/Documents/%sXXXXXX", homeStr, prefix);
+        fd = mkstemp(*filename);
+    }
+#endif
 #endif
     /* -----common section-----*/
     if (fd < 0) {