Implement localBranchWithName()

SwiftGit2/Repository.swift

@@ -252,8 +252,20 @@ final public class Repository {
 		return failure()
 	}
 	
-	public func branchWithName(name: String) -> Result<Branch> {
-		return failure()
+	public func localBranchWithName(name: String) -> Result<Branch> {
+		let pointer = UnsafeMutablePointer<COpaquePointer>.alloc(1)
+		let repository = self.pointer
+		let result = git_branch_lookup(pointer, repository, name.cStringUsingEncoding(NSUTF8StringEncoding)!, GIT_BRANCH_LOCAL)
+		
+		if result != GIT_OK.value {
+			pointer.dealloc(1)
+			return failure()
+		}
+		
+		let value = Branch(pointer.memory)!
+		git_reference_free(pointer.memory)
+		pointer.dealloc(1)
+		return success(value)
 	}
 	
 	public func allTags() -> Result<[TagReference]> {

SwiftGit2Tests/RepositorySpec.swift

@@ -309,5 +309,17 @@ class RepositorySpec: QuickSpec {
 				expect(result.error()).notTo(beNil())
 			}
 		}
+		
+		describe("-localBranchWithName()") {
+			it("should return the branch if it exists") {
+				let result = Fixtures.simpleRepository.localBranchWithName("master")
+				expect(result.value()?.longName).to(equal("refs/heads/master"))
+			}
+			
+			it("should error if the branch doesn't exists") {
+				let result = Fixtures.simpleRepository.localBranchWithName("nonexistent")
+				expect(result.error()).notTo(beNil())
+			}
+		}
 	}
 }