only process for face feature

bf/bf/BetterFaceClass/UIImageView+BetterFace.m

@@ -101,7 +101,8 @@ - (void)faceDetect:(UIImage *)aImage
 
         NSArray* features = [detector featuresInImage:image];
 
-        if ([features count] == 0) {
+        NSInteger faceFeatureCount = [self countOfFaceFeatureWithFeatures:features];
+        if (faceFeatureCount == 0) {
             BFLog(@"no faces");
             dispatch_async(dispatch_get_main_queue(), ^{
                 [[self imageLayer] removeFromSuperlayer];
@@ -115,6 +116,16 @@ - (void)faceDetect:(UIImage *)aImage
     });
 }
 
+- (NSUInteger)countOfFaceFeatureWithFeatures:(NSArray *)features {
+    NSUInteger count = 0;
+    for (CIFeature *feature in features) {
+        if ([feature.type isEqualToString:CIFeatureTypeFace]) {
+            count++;
+        }
+    }
+    return count;
+}
+
 -(void)markAfterFaceDetect:(NSArray *)features size:(CGSize)size{
     CGRect fixedRect = CGRectMake(MAXFLOAT, MAXFLOAT, 0, 0);
     CGFloat rightBorder = 0, bottomBorder = 0;