add helper methods to ReturnCode

android/ffmpeg-kit-android-lib/src/main/java/com/arthenica/ffmpegkit/ReturnCode.java

@@ -31,6 +31,14 @@ public class ReturnCode {
         this.value = value;
     }
 
+    public static boolean isSuccess(final ReturnCode returnCode) {
+        return (returnCode != null && returnCode.getValue() == SUCCESS);
+    }
+
+    public static boolean isCancel(final ReturnCode returnCode) {
+        return (returnCode != null && returnCode.getValue() == CANCEL);
+    }
+
     public int getValue() {
         return value;
     }

apple/src/ReturnCode.h

@@ -31,6 +31,10 @@ typedef NS_ENUM(NSUInteger, ReturnCodeEnum) {
 
 - (instancetype)init:(int)value;
 
++ (BOOL)isSuccess:(ReturnCode*)value;
+
++ (BOOL)isCancel:(ReturnCode*)value;
+
 - (int)getValue;
 
 - (BOOL)isSuccess;

apple/src/ReturnCode.m

@@ -32,6 +32,14 @@
     return self;
 }
 
++ (BOOL)isSuccess:(ReturnCode*)value {
+    return (value != nil) && ([value getValue] == ReturnCodeSuccess);
+}
+
++ (BOOL)isCancel:(ReturnCode*)value {
+    return (value != nil) && ([value getValue] == ReturnCodeCancel);
+}
+
 - (int)getValue {
     return _value;
 }