Merge pull request #1712 from dkharrat/swift-error-handling

add nullable qualifier to return types that can be nil, to support Swift 2 try-catch syntax

objectivec/GPBMessage.h

@@ -97,7 +97,7 @@ CF_EXTERN_C_END
 ///                 the data can not be parsed.
 ///
 /// @return A new instance of the class messaged.
-+ (instancetype)parseFromData:(NSData *)data error:(NSError **)errorPtr;
++ (nullable instancetype)parseFromData:(NSData *)data error:(NSError **)errorPtr;
 
 /// Creates a new instance by parsing the data. This method should be sent to
 /// the generated message class that the data should be interpreted as. If
@@ -116,7 +116,7 @@ CF_EXTERN_C_END
 ///                          reason if the data can not be parsed.
 ///
 /// @return A new instance of the class messaged.
-+ (instancetype)parseFromData:(NSData *)data
++ (nullable instancetype)parseFromData:(NSData *)data
                      extensionRegistry:(nullable GPBExtensionRegistry *)extensionRegistry
                                  error:(NSError **)errorPtr;
 
@@ -137,7 +137,7 @@ CF_EXTERN_C_END
 ///                          reason if the data can not be parsed.
 ///
 /// @return A new instance of the class messaged.
-+ (instancetype)parseFromCodedInputStream:(GPBCodedInputStream *)input
++ (nullable instancetype)parseFromCodedInputStream:(GPBCodedInputStream *)input
                                  extensionRegistry:
                                      (nullable GPBExtensionRegistry *)extensionRegistry
                                              error:(NSError **)errorPtr;
@@ -160,7 +160,7 @@ CF_EXTERN_C_END
 ///                          reason if the data can not be parsed.
 ///
 /// @return A new instance of the class messaged.
-+ (instancetype)parseDelimitedFromCodedInputStream:(GPBCodedInputStream *)input
++ (nullable instancetype)parseDelimitedFromCodedInputStream:(GPBCodedInputStream *)input
                                           extensionRegistry:
                                               (nullable GPBExtensionRegistry *)extensionRegistry
                                                       error:(NSError **)errorPtr;
@@ -179,7 +179,7 @@ CF_EXTERN_C_END
 /// @param data     The data to parse.
 /// @param errorPtr An optional error pointer to fill in with a failure reason if
 ///                 the data can not be parsed.
-- (instancetype)initWithData:(NSData *)data error:(NSError **)errorPtr;
+- (nullable instancetype)initWithData:(NSData *)data error:(NSError **)errorPtr;
 
 /// Initializes an instance by parsing the data. This method should be sent to
 /// the generated message class that the data should be interpreted as. If
@@ -196,7 +196,7 @@ CF_EXTERN_C_END
 /// @param extensionRegistry The extension registry to use to look up extensions.
 /// @param errorPtr          An optional error pointer to fill in with a failure
 ///                          reason if the data can not be parsed.
-- (instancetype)initWithData:(NSData *)data
+- (nullable instancetype)initWithData:(NSData *)data
                     extensionRegistry:(nullable GPBExtensionRegistry *)extensionRegistry
                                 error:(NSError **)errorPtr;
 
@@ -216,7 +216,7 @@ CF_EXTERN_C_END
 /// @param extensionRegistry The extension registry to use to look up extensions.
 /// @param errorPtr          An optional error pointer to fill in with a failure
 ///                          reason if the data can not be parsed.
-- (instancetype)initWithCodedInputStream:(GPBCodedInputStream *)input
+- (nullable instancetype)initWithCodedInputStream:(GPBCodedInputStream *)input
                                 extensionRegistry:
                                     (nullable GPBExtensionRegistry *)extensionRegistry
                                             error:(NSError **)errorPtr;

objectivec/Tests/GPBSwiftTests.swift

@@ -446,7 +446,7 @@ class GPBBridgeTests: XCTestCase {
 
     let data = msg.data()
 
-    let msg2 = Message2(data: data!, error:nil)
+    let msg2 = try! Message2(data: data!)
     XCTAssertTrue(msg2 !== msg)  // New instance
     XCTAssertEqual(msg.optionalInt32, Int32(100))
     XCTAssertEqual(msg.optionalInt64, Int64(101))