My clang now doesn't complain about !"foo".

src/utils/ios/SkOSFile_iOS.mm

 /*
  * Copyright 2010 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include <Foundation/Foundation.h>
 #include "SkOSFile.h"
 #include "SkString.h"
@@ skipping 64 matching lines @@
             byteCount = remaining;
         }
         memcpy(buffer, (char*)[rec->fData bytes] + rec->fOffset, byteCount);
         rec->fOffset += byteCount;
         SkASSERT(rec->fOffset <= rec->fLength);
         return byteCount;
     }
 }
 
 size_t sk_fwrite(const void* buffer, size_t byteCount, SkFILE* f) {
-    SkASSERT(!"Not supported yet");
+    SkDEBUGFAIL("Not supported yet");
     return 0;
 }
 
 void sk_fflush(SkFILE* f) {
-    SkASSERT(!"Not supported yet");
+    SkDEBUGFAIL("Not supported yet");
 }
 
 void sk_fclose(SkFILE* rec) {
     SkASSERT(rec);
     [rec->fData release];
     delete rec;
 }