提交：修改周边搜索代码；

example/lib/main.dart

@@ -29,7 +29,7 @@ class _MyAppState extends State<MyApp> {
     // var result1 = await ClxMapPoiSearch.instance.aroundSearch(31.230378, 121.473658);
     // print("------ result1: $result1");
 
-    var result2 = await ClxMapPoiSearch.instance.aroundSearchAll("卫生间", city: "南京",);
+    var result2 = await ClxMapPoiSearch.instance.aroundSearchAll("停车场", city: "南京",);
     print("------ result2: $result2");
 
   }

ios/Classes/ClxMapPoiSearchPlugin.m

@@ -111,7 +111,7 @@
     NSString *keywords = arguments[@"keywords"];
     NSString *city = arguments[@"city"];
     
-    if ((latitude != nil && [latitude intValue] != 0) && (longitude != nil && [longitude intValue] != 0)) {
+    if (![latitude isKindOfClass:[NSNull class]] && ![longitude isKindOfClass:[NSNull class]]) {
         NSLog(@"aroundSearchAll 经纬度不为0 - latitude:%@, longitude:%@", latitude, longitude);
 
         AMapPOIAroundSearchRequest *request = [[AMapPOIAroundSearchRequest alloc] init];
@@ -119,10 +119,10 @@
         request.page = 1;
         request.offset = 20;
         request.radius = 1000;
-        if (keywords != nil && [keywords isKindOfClass:[NSNull class]]) {
+        if (![keywords isKindOfClass:[NSNull class]]) {
             request.keywords = keywords;
         }
-        if (city != nil && ![city isKindOfClass:[NSNull class]]) {
+        if (![city isKindOfClass:[NSNull class]]) {
             request.city = city;
         }
         [self.search AMapPOIAroundSearch:request];
@@ -130,7 +130,12 @@
         NSLog(@"aroundSearchAll 经纬度为0 - latitude:%@, longitude:%@", latitude, longitude);
 
         AMapPOIKeywordsSearchRequest *request = [[AMapPOIKeywordsSearchRequest alloc] init];
+        if (![keywords isKindOfClass:[NSNull class]]) {
             request.keywords = keywords;
+        }
+        if (![city isKindOfClass:[NSNull class]]) {
+            request.city = city;
+        }
         request.cityLimit = YES;
         request.page = 1;
         request.offset = 20;