docs: refine

Chapter1 - iOS/1.100.md

@@ -180,4 +180,34 @@ if (self.socket == NULL) {
     [_delegates setObject:delegate forKey:task];
     [task resume];
 }
+```
+
+### NSURLProtocol 主意事项
+使用 NSURLProtocol 的时候，如果是代理 NSURLSession 的网络请求，则需要重写 protocolClasses 方法。但是在你往给方法设置 protocolClasses 的时候可能全局也有其他 SDK、工具类也做了修改。这样子需要注意不能丢弃别人的，也不能丢弃自己的。参考 OHHTTPStubs 在注册 NSURLProtocol 子类的处理
+```
++ (void)setEnabled:(BOOL)enable forSessionConfiguration:(NSURLSessionConfiguration*)sessionConfig
+{
+    // Runtime check to make sure the API is available on this version
+    if (   [sessionConfig respondsToSelector:@selector(protocolClasses)]
+        && [sessionConfig respondsToSelector:@selector(setProtocolClasses:)])
+    {
+        NSMutableArray * urlProtocolClasses = [NSMutableArray arrayWithArray:sessionConfig.protocolClasses];
+        Class protoCls = HTTPStubsProtocol.class;
+        if (enable && ![urlProtocolClasses containsObject:protoCls])
+        {
+            [urlProtocolClasses insertObject:protoCls atIndex:0];
+        }
+        else if (!enable && [urlProtocolClasses containsObject:protoCls])
+        {
+            [urlProtocolClasses removeObject:protoCls];
+        }
+        sessionConfig.protocolClasses = urlProtocolClasses;
+    }
+    else
+    {
+        NSLog(@"[OHHTTPStubs] %@ is only available when running on iOS7+/OSX9+. "
+              @"Use conditions like 'if ([NSURLSessionConfiguration class])' to only call "
+              @"this method if the user is running iOS7+/OSX9+.", NSStringFromSelector(_cmd));
+    }
+}
 ```