diff --git a/ios/sdk/WeexSDK/Sources/Utility/WXConvert.m b/ios/sdk/WeexSDK/Sources/Utility/WXConvert.m
index c497d280c8..b0de541875 100644
--- a/ios/sdk/WeexSDK/Sources/Utility/WXConvert.m
+++ b/ios/sdk/WeexSDK/Sources/Utility/WXConvert.m
@@ -503,32 +503,32 @@ + (WXTextStyle)WXTextStyle:(id)value
 
 + (CGFloat)WXTextWeight:(id)value
 {
-    if([value isKindOfClass:[NSString class]]){
-        NSString *string = (NSString *)value;
-        if ([string isEqualToString:@"normal"])
-            return WX_SYS_VERSION_LESS_THAN(@"8.2")?0:UIFontWeightRegular;
-        else if ([string isEqualToString:@"bold"])
-            return WX_SYS_VERSION_LESS_THAN(@"8.2")?0.4:UIFontWeightBold;
-        else if ([string isEqualToString:@"100"])
-            return WX_SYS_VERSION_LESS_THAN(@"8.2")?-0.8:UIFontWeightUltraLight;
-        else if ([string isEqualToString:@"200"])
-            return WX_SYS_VERSION_LESS_THAN(@"8.2")?-0.6:UIFontWeightThin;
-        else if ([string isEqualToString:@"300"])
-            return WX_SYS_VERSION_LESS_THAN(@"8.2")?-0.4:UIFontWeightLight;
-        else if ([string isEqualToString:@"400"])
-            return WX_SYS_VERSION_LESS_THAN(@"8.2")?0:UIFontWeightRegular;
-        else if ([string isEqualToString:@"500"])
-            return WX_SYS_VERSION_LESS_THAN(@"8.2")?0.23:UIFontWeightMedium;
-        else if ([string isEqualToString:@"600"])
-            return WX_SYS_VERSION_LESS_THAN(@"8.2")?0.3:UIFontWeightSemibold;
-        else if ([string isEqualToString:@"700"])
-            return WX_SYS_VERSION_LESS_THAN(@"8.2")?0.4:UIFontWeightBold;
-        else if ([string isEqualToString:@"800"])
-            return WX_SYS_VERSION_LESS_THAN(@"8.2")?0.56:UIFontWeightHeavy;
-        else if ([string isEqualToString:@"900"])
-            return WX_SYS_VERSION_LESS_THAN(@"8.2")?0.62:UIFontWeightBlack;
-
-    }
+    NSString *string = [WXConvert NSString:value];
+    if (!string)
+        return WX_SYS_VERSION_LESS_THAN(@"8.2")?0:UIFontWeightRegular;
+    else if ([string isEqualToString:@"normal"])
+        return WX_SYS_VERSION_LESS_THAN(@"8.2")?0:UIFontWeightRegular;
+    else if ([string isEqualToString:@"bold"])
+        return WX_SYS_VERSION_LESS_THAN(@"8.2")?0.4:UIFontWeightBold;
+    else if ([string isEqualToString:@"100"])
+        return WX_SYS_VERSION_LESS_THAN(@"8.2")?-0.8:UIFontWeightUltraLight;
+    else if ([string isEqualToString:@"200"])
+        return WX_SYS_VERSION_LESS_THAN(@"8.2")?-0.6:UIFontWeightThin;
+    else if ([string isEqualToString:@"300"])
+        return WX_SYS_VERSION_LESS_THAN(@"8.2")?-0.4:UIFontWeightLight;
+    else if ([string isEqualToString:@"400"])
+        return WX_SYS_VERSION_LESS_THAN(@"8.2")?0:UIFontWeightRegular;
+    else if ([string isEqualToString:@"500"])
+        return WX_SYS_VERSION_LESS_THAN(@"8.2")?0.23:UIFontWeightMedium;
+    else if ([string isEqualToString:@"600"])
+        return WX_SYS_VERSION_LESS_THAN(@"8.2")?0.3:UIFontWeightSemibold;
+    else if ([string isEqualToString:@"700"])
+        return WX_SYS_VERSION_LESS_THAN(@"8.2")?0.4:UIFontWeightBold;
+    else if ([string isEqualToString:@"800"])
+        return WX_SYS_VERSION_LESS_THAN(@"8.2")?0.56:UIFontWeightHeavy;
+    else if ([string isEqualToString:@"900"])
+        return WX_SYS_VERSION_LESS_THAN(@"8.2")?0.62:UIFontWeightBlack;
+        
     return WX_SYS_VERSION_LESS_THAN(@"8.2")?0:UIFontWeightRegular;
 }