Feature: add redirection to NSLog, if KIVY_NSLOG=1 is set

kivy_ios/recipes/ios/src/ios.pyx

@@ -22,6 +22,7 @@ cdef extern from "ios_wrapper.h":
     void load_url_webview(char *url, int x, int y, int width, int height)
     float ios_uiscreen_get_scale()
     int ios_uiscreen_get_dpi()
+    void ios_nslog(char *str)
     padding ios_get_safe_area()
 
 cdef void _send_email_done(char *status, void *data):
@@ -217,6 +218,22 @@ def get_safe_area():
     '''
     return ios_get_safe_area()
 
+def nslog(message):
+    '''Log a message to the console using NSLog
+
+    :Parameters:
+        `message`: str
+            The message to log
+    '''
+    cdef char *j_message = NULL
+
+    if message is not None:
+        if type(message) is unicode:
+            message = message.encode('UTF-8')
+        j_message = <bytes>message
+
+    ios_nslog(j_message)
+
 
 from pyobjus import autoclass, selector, protocol
 from pyobjus.protocols import protocols

kivy_ios/recipes/ios/src/ios_utils.m

@@ -171,3 +171,7 @@ padding ios_get_safe_area() {
 	}	
 	return safearea;
 }
+
+void ios_nslog(char *str) {
+    NSLog(@"%s", str);
+}

kivy_ios/recipes/ios/src/ios_wrapper.h

@@ -19,4 +19,6 @@ typedef void (*ios_send_email_cb)(char *, void *);
 int ios_send_email(char *subject, char *text, char *mimetype, char *filename,
 	char *filename_alias, ios_send_email_cb callback, void *userdata);
 
+void ios_nslog(char *str);
+
 #endif

kivy_ios/tools/templates/{{ cookiecutter.project_name }}-ios/main.m

@@ -45,6 +45,10 @@ int main(int argc, char *argv[]) {
     putenv("KIVY_NO_CONSOLELOG=1");
     #endif
 
+    // In production, if you want to redirect stdout/stderr to NSLog, uncomment
+    // the following line. This is useful to debug python errors in production.
+    //putenv("KIVY_NSLOG=1");
+
     // Export orientation preferences for Kivy
     export_orientation();
 
@@ -156,6 +160,23 @@ void load_custom_builtin_importer() {
         "        def flush(self, *args, **kw): pass\n" \
         "    sys.stdout = fakestd()\n" \
         "    sys.stderr = fakestd()\n" \
+        "else if environ.get('KIVY_NSLOG', '1') == '1':\n" \
+        "   from ios import nslog\n" \
+        "   class NslogRedirect(object):\n" \
+        "       def __init__(self):\n" \
+        "           self.buffer = ""\n" \
+        "       def write(self, chunk):\n" \
+        "           self.buffer += chunk\n" \
+        "           if '\n' in self.buffer:\n" \
+        "               lines = self.buffer.split('\n')\n" \
+        "               for line in lines[:-1]:\n" \
+        "                   nslog(line)\n" \
+        "               self.buffer = lines[-1]\n" \
+        "       def flush(self):\n" \
+        "           nslog(self.buffer)\n" \
+        "           self.buffer = ""\n" \
+        "    sys.stdout = NslogRedirect()\n" \
+        "    sys.stderr = NslogRedirect()\n" \
         "# Custom builtin importer for precompiled modules\n" \
         "class CustomBuiltinImporter(object):\n" \
         "    def find_module(self, fullname, mpath=None):\n" \