diff --git a/examples/Cargo.toml b/examples/Cargo.toml
index 423ffe021..a25f526f1 100644
--- a/examples/Cargo.toml
+++ b/examples/Cargo.toml
@@ -6,7 +6,7 @@ edition = "2018"
 
 [dev-dependencies]
 tokio = { version = "0.2.0", path = "../tokio", features = ["full"] }
-tokio-util = { version = "0.2.0", path = "../tokio-util", features = ["full"] }
+tokio-util = { version = "0.3.0", path = "../tokio-util", features = ["full"] }
 bytes = "0.5"
 futures = "0.3.0"
 http = "0.2"
diff --git a/examples/chat.rs b/examples/chat.rs
index fac43cbf0..b3fb727a2 100644
--- a/examples/chat.rs
+++ b/examples/chat.rs
@@ -193,9 +193,7 @@ async fn process(
     let mut lines = Framed::new(stream, LinesCodec::new());
 
     // Send a prompt to the client to enter their username.
-    lines
-        .send(String::from("Please enter your username:"))
-        .await?;
+    lines.send("Please enter your username:").await?;
 
     // Read the first line from the `LineCodec` stream to get the username.
     let username = match lines.next().await {
@@ -232,7 +230,7 @@ async fn process(
             // A message was received from a peer. Send it to the
             // current user.
             Ok(Message::Received(msg)) => {
-                peer.lines.send(msg).await?;
+                peer.lines.send(&msg).await?;
             }
             Err(e) => {
                 println!(
diff --git a/examples/tinydb.rs b/examples/tinydb.rs
index 7c71dedf6..c1af2541f 100644
--- a/examples/tinydb.rs
+++ b/examples/tinydb.rs
@@ -130,7 +130,7 @@ async fn main() -> Result<(), Box<dyn Error>> {
 
                                 let response = response.serialize();
 
-                                if let Err(e) = lines.send(response).await {
+                                if let Err(e) = lines.send(response.as_str()).await {
                                     println!("error on sending response; error = {:?}", e);
                                 }
                             }
diff --git a/examples/tinyhttp.rs b/examples/tinyhttp.rs
index 9ac2806e9..732da0d64 100644
--- a/examples/tinyhttp.rs
+++ b/examples/tinyhttp.rs
@@ -96,8 +96,7 @@ struct Http;
 
 /// Implementation of encoding an HTTP response into a `BytesMut`, basically
 /// just writing out an HTTP/1.1 response.
-impl Encoder for Http {
-    type Item = Response<String>;
+impl Encoder<Response<String>> for Http {
     type Error = io::Error;
 
     fn encode(&mut self, item: Response<String>, dst: &mut BytesMut) -> io::Result<()> {
diff --git a/tokio-tls/Cargo.toml b/tokio-tls/Cargo.toml
index d5a5c6def..a98779269 100644
--- a/tokio-tls/Cargo.toml
+++ b/tokio-tls/Cargo.toml
@@ -30,7 +30,7 @@ tokio = { version = "0.2.0", path = "../tokio" }
 
 [dev-dependencies]
 tokio = { version = "0.2.0", path = "../tokio", features = ["macros", "stream", "rt-core", "io-util", "net"] }
-tokio-util = { version = "0.2.0", path = "../tokio-util", features = ["full"] }
+tokio-util = { version = "0.3.0", path = "../tokio-util", features = ["full"] }
 
 cfg-if = "0.1"
 env_logger = { version = "0.6", default-features = false }
diff --git a/tokio-util/CHANGELOG.md b/tokio-util/CHANGELOG.md
index 48022e343..aaabd106d 100644
--- a/tokio-util/CHANGELOG.md
+++ b/tokio-util/CHANGELOG.md
@@ -1,3 +1,14 @@
+# 0.3.0 (February 28, 2020)
+
+Breaking changes:
+
+- Change codec::Encoder trait to take a generic Item parameter (#1746), which allows
+  codec writers to pass references into `Framed` and `FramedWrite` types.
+
+Other additions:
+
+- Add futures-io/tokio::io compatibility layer (#2117)
+
 # 0.2.0 (November 26, 2019)
 
 - Initial release
diff --git a/tokio-util/Cargo.toml b/tokio-util/Cargo.toml
index e029de2f6..9a537ba15 100644
--- a/tokio-util/Cargo.toml
+++ b/tokio-util/Cargo.toml
@@ -7,7 +7,7 @@ name = "tokio-util"
 #   - Cargo.toml
 # - Update CHANGELOG.md.
 # - Create "v0.2.x" git tag.
-version = "0.2.0"
+version = "0.3.0"
 edition = "2018"
 authors = ["Tokio Contributors <team@tokio.rs>"]
 license = "MIT"
@@ -38,7 +38,7 @@ futures-core = "0.3.0"
 futures-sink = "0.3.0"
 futures-io = { version = "0.3.0", optional = true }
 log = "0.4"
-pin-project-lite = "0.1.1"
+pin-project-lite = "0.1.4"
 
 [dev-dependencies]
 tokio = { version = "0.2.0", path = "../tokio", features = ["full"] }
diff --git a/tokio-util/src/codec/bytes_codec.rs b/tokio-util/src/codec/bytes_codec.rs
index 46b31aa32..a5e73749e 100644
--- a/tokio-util/src/codec/bytes_codec.rs
+++ b/tokio-util/src/codec/bytes_codec.rs
@@ -65,8 +65,7 @@ impl Decoder for BytesCodec {
     }
 }
 
-impl Encoder for BytesCodec {
-    type Item = Bytes;
+impl Encoder<Bytes> for BytesCodec {
     type Error = io::Error;
 
     fn encode(&mut self, data: Bytes, buf: &mut BytesMut) -> Result<(), io::Error> {
diff --git a/tokio-util/src/codec/decoder.rs b/tokio-util/src/codec/decoder.rs
index 5f53ebc31..84d27fbf1 100644
--- a/tokio-util/src/codec/decoder.rs
+++ b/tokio-util/src/codec/decoder.rs
@@ -1,4 +1,3 @@
-use crate::codec::encoder::Encoder;
 use crate::codec::Framed;
 
 use tokio::io::{AsyncRead, AsyncWrite};
@@ -159,7 +158,7 @@ pub trait Decoder {
     /// [`Framed`]: crate::codec::Framed
     fn framed<T: AsyncRead + AsyncWrite + Sized>(self, io: T) -> Framed<T, Self>
     where
-        Self: Encoder + Sized,
+        Self: Sized,
     {
         Framed::new(io, self)
     }
diff --git a/tokio-util/src/codec/encoder.rs b/tokio-util/src/codec/encoder.rs
index e33e66849..770a10fa9 100644
--- a/tokio-util/src/codec/encoder.rs
+++ b/tokio-util/src/codec/encoder.rs
@@ -5,10 +5,7 @@ use std::io;
 /// [`FramedWrite`].
 ///
 /// [`FramedWrite`]: crate::codec::FramedWrite
-pub trait Encoder {
-    /// The type of items consumed by the `Encoder`
-    type Item;
-
+pub trait Encoder<Item> {
     /// The type of encoding errors.
     ///
     /// [`FramedWrite`] requires `Encoder`s errors to implement `From<io::Error>`
@@ -24,5 +21,5 @@ pub trait Encoder {
     /// will be written out when possible.
     ///
     /// [`FramedWrite`]: crate::codec::FramedWrite
-    fn encode(&mut self, item: Self::Item, dst: &mut BytesMut) -> Result<(), Self::Error>;
+    fn encode(&mut self, item: Item, dst: &mut BytesMut) -> Result<(), Self::Error>;
 }
diff --git a/tokio-util/src/codec/framed.rs b/tokio-util/src/codec/framed.rs
index e42ed28ca..d2e7659ed 100644
--- a/tokio-util/src/codec/framed.rs
+++ b/tokio-util/src/codec/framed.rs
@@ -67,7 +67,6 @@ impl<T, U> ProjectFuse for Fuse<T, U> {
 impl<T, U> Framed<T, U>
 where
     T: AsyncRead + AsyncWrite,
-    U: Decoder + Encoder,
 {
     /// Provides a [`Stream`] and [`Sink`] interface for reading and writing to this
     /// I/O object, using [`Decoder`] and [`Encoder`] to read and write the raw data.
@@ -262,7 +261,7 @@ where
 impl<T, I, U> Sink<I> for Framed<T, U>
 where
     T: AsyncWrite,
-    U: Encoder<Item = I>,
+    U: Encoder<I>,
     U::Error: From<io::Error>,
 {
     type Error = U::Error;
@@ -380,11 +379,10 @@ impl<T, U: Decoder> Decoder for Fuse<T, U> {
     }
 }
 
-impl<T, U: Encoder> Encoder for Fuse<T, U> {
-    type Item = U::Item;
+impl<T, I, U: Encoder<I>> Encoder<I> for Fuse<T, U> {
     type Error = U::Error;
 
-    fn encode(&mut self, item: Self::Item, dst: &mut BytesMut) -> Result<(), Self::Error> {
+    fn encode(&mut self, item: I, dst: &mut BytesMut) -> Result<(), Self::Error> {
         self.codec.encode(item, dst)
     }
 }
@@ -414,8 +412,11 @@ pub struct FramedParts<T, U> {
 }
 
 impl<T, U> FramedParts<T, U> {
-    /// Create a new, default, `FramedParts`.
-    pub fn new(io: T, codec: U) -> FramedParts<T, U> {
+    /// Create a new, default, `FramedParts`
+    pub fn new<I>(io: T, codec: U) -> FramedParts<T, U>
+    where
+        U: Encoder<I>,
+    {
         FramedParts {
             io,
             codec,
diff --git a/tokio-util/src/codec/framed_write.rs b/tokio-util/src/codec/framed_write.rs
index 80aa21c60..c0049b2d0 100644
--- a/tokio-util/src/codec/framed_write.rs
+++ b/tokio-util/src/codec/framed_write.rs
@@ -42,7 +42,6 @@ const BACKPRESSURE_BOUNDARY: usize = INITIAL_CAPACITY;
 impl<T, E> FramedWrite<T, E>
 where
     T: AsyncWrite,
-    E: Encoder,
 {
     /// Creates a new `FramedWrite` with the given `encoder`.
     pub fn new(inner: T, encoder: E) -> FramedWrite<T, E> {
@@ -100,7 +99,7 @@ impl<T, E> FramedWrite<T, E> {
 impl<T, I, E> Sink<I> for FramedWrite<T, E>
 where
     T: AsyncWrite,
-    E: Encoder<Item = I>,
+    E: Encoder<I>,
     E::Error: From<io::Error>,
 {
     type Error = E::Error;
@@ -191,9 +190,9 @@ impl<T> FramedWrite2<T> {
 impl<I, T> Sink<I> for FramedWrite2<T>
 where
     T: ProjectFuse + AsyncWrite,
-    T::Codec: Encoder<Item = I>,
+    T::Codec: Encoder<I>,
 {
-    type Error = <T::Codec as Encoder>::Error;
+    type Error = <T::Codec as Encoder<I>>::Error;
 
     fn poll_ready(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
         // If the buffer is already over 8KiB, then attempt to flush it. If after flushing it's
diff --git a/tokio-util/src/codec/length_delimited.rs b/tokio-util/src/codec/length_delimited.rs
index 04061c0ac..5e98d4a70 100644
--- a/tokio-util/src/codec/length_delimited.rs
+++ b/tokio-util/src/codec/length_delimited.rs
@@ -546,12 +546,11 @@ impl Decoder for LengthDelimitedCodec {
     }
 }
 
-impl Encoder for LengthDelimitedCodec {
-    type Item = Bytes;
+impl Encoder<Bytes> for LengthDelimitedCodec {
     type Error = io::Error;
 
     fn encode(&mut self, data: Bytes, dst: &mut BytesMut) -> Result<(), io::Error> {
-        let n = (&data).remaining();
+        let n = data.len();
 
         if n > self.builder.max_frame_len {
             return Err(io::Error::new(
diff --git a/tokio-util/src/codec/lines_codec.rs b/tokio-util/src/codec/lines_codec.rs
index e048b287c..e1816d8c4 100644
--- a/tokio-util/src/codec/lines_codec.rs
+++ b/tokio-util/src/codec/lines_codec.rs
@@ -182,11 +182,14 @@ impl Decoder for LinesCodec {
     }
 }
 
-impl Encoder for LinesCodec {
-    type Item = String;
+impl<T> Encoder<T> for LinesCodec
+where
+    T: AsRef<str>,
+{
     type Error = LinesCodecError;
 
-    fn encode(&mut self, line: String, buf: &mut BytesMut) -> Result<(), LinesCodecError> {
+    fn encode(&mut self, line: T, buf: &mut BytesMut) -> Result<(), LinesCodecError> {
+        let line = line.as_ref();
         buf.reserve(line.len() + 1);
         buf.put(line.as_bytes());
         buf.put_u8(b'\n');
diff --git a/tokio-util/src/udp/frame.rs b/tokio-util/src/udp/frame.rs
index c16e12f88..5b098bd49 100644
--- a/tokio-util/src/udp/frame.rs
+++ b/tokio-util/src/udp/frame.rs
@@ -70,7 +70,7 @@ impl<C: Decoder + Unpin> Stream for UdpFramed<C> {
     }
 }
 
-impl<C: Encoder + Unpin> Sink<(C::Item, SocketAddr)> for UdpFramed<C> {
+impl<I, C: Encoder<I> + Unpin> Sink<(I, SocketAddr)> for UdpFramed<C> {
     type Error = C::Error;
 
     fn poll_ready(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
@@ -84,7 +84,7 @@ impl<C: Encoder + Unpin> Sink<(C::Item, SocketAddr)> for UdpFramed<C> {
         Poll::Ready(Ok(()))
     }
 
-    fn start_send(self: Pin<&mut Self>, item: (C::Item, SocketAddr)) -> Result<(), Self::Error> {
+    fn start_send(self: Pin<&mut Self>, item: (I, SocketAddr)) -> Result<(), Self::Error> {
         let (frame, out_addr) = item;
 
         let pin = self.get_mut();
diff --git a/tokio-util/tests/codecs.rs b/tokio-util/tests/codecs.rs
index d12128665..a22effbeb 100644
--- a/tokio-util/tests/codecs.rs
+++ b/tokio-util/tests/codecs.rs
@@ -209,9 +209,9 @@ fn lines_encoder() {
     let mut codec = LinesCodec::new();
     let mut buf = BytesMut::new();
 
-    codec.encode(String::from("line 1"), &mut buf).unwrap();
+    codec.encode("line 1", &mut buf).unwrap();
     assert_eq!("line 1\n", buf);
 
-    codec.encode(String::from("line 2"), &mut buf).unwrap();
+    codec.encode("line 2", &mut buf).unwrap();
     assert_eq!("line 1\nline 2\n", buf);
 }
diff --git a/tokio-util/tests/framed.rs b/tokio-util/tests/framed.rs
index cb82f8df8..d7ee3ef51 100644
--- a/tokio-util/tests/framed.rs
+++ b/tokio-util/tests/framed.rs
@@ -28,8 +28,7 @@ impl Decoder for U32Codec {
     }
 }
 
-impl Encoder for U32Codec {
-    type Item = u32;
+impl Encoder<u32> for U32Codec {
     type Error = io::Error;
 
     fn encode(&mut self, item: u32, dst: &mut BytesMut) -> io::Result<()> {
diff --git a/tokio-util/tests/framed_write.rs b/tokio-util/tests/framed_write.rs
index b2970c39d..9ac6c1d11 100644
--- a/tokio-util/tests/framed_write.rs
+++ b/tokio-util/tests/framed_write.rs
@@ -28,8 +28,7 @@ macro_rules! pin {
 
 struct U32Encoder;
 
-impl Encoder for U32Encoder {
-    type Item = u32;
+impl Encoder<u32> for U32Encoder {
     type Error = io::Error;
 
     fn encode(&mut self, item: u32, dst: &mut BytesMut) -> io::Result<()> {
diff --git a/tokio-util/tests/udp.rs b/tokio-util/tests/udp.rs
index 51c65c630..0ba057428 100644
--- a/tokio-util/tests/udp.rs
+++ b/tokio-util/tests/udp.rs
@@ -8,6 +8,7 @@ use futures::future::FutureExt;
 use futures::sink::SinkExt;
 use std::io;
 
+#[cfg_attr(any(target_os = "macos", target_os = "ios"), allow(unused_assignments))]
 #[tokio::test]
 async fn send_framed() -> std::io::Result<()> {
     let mut a_soc = UdpSocket::bind("127.0.0.1:0").await?;
@@ -21,33 +22,34 @@ async fn send_framed() -> std::io::Result<()> {
         let mut a = UdpFramed::new(a_soc, ByteCodec);
         let mut b = UdpFramed::new(b_soc, ByteCodec);
 
-        let msg = b"4567".to_vec();
+        let msg = b"4567";
 
-        let send = a.send((msg.clone(), b_addr));
+        let send = a.send((msg, b_addr));
         let recv = b.next().map(|e| e.unwrap());
         let (_, received) = try_join(send, recv).await.unwrap();
 
         let (data, addr) = received;
-        assert_eq!(msg, data);
+        assert_eq!(msg, &*data);
         assert_eq!(a_addr, addr);
 
         a_soc = a.into_inner();
         b_soc = b.into_inner();
     }
 
+    #[cfg(not(any(target_os = "macos", target_os = "ios")))]
     // test sending & receiving an empty message
     {
         let mut a = UdpFramed::new(a_soc, ByteCodec);
         let mut b = UdpFramed::new(b_soc, ByteCodec);
 
-        let msg = b"".to_vec();
+        let msg = b"";
 
-        let send = a.send((msg.clone(), b_addr));
+        let send = a.send((msg, b_addr));
         let recv = b.next().map(|e| e.unwrap());
         let (_, received) = try_join(send, recv).await.unwrap();
 
         let (data, addr) = received;
-        assert_eq!(msg, data);
+        assert_eq!(msg, &*data);
         assert_eq!(a_addr, addr);
     }
 
@@ -66,13 +68,12 @@ impl Decoder for ByteCodec {
     }
 }
 
-impl Encoder for ByteCodec {
-    type Item = Vec<u8>;
+impl Encoder<&[u8]> for ByteCodec {
     type Error = io::Error;
 
-    fn encode(&mut self, data: Vec<u8>, buf: &mut BytesMut) -> Result<(), io::Error> {
+    fn encode(&mut self, data: &[u8], buf: &mut BytesMut) -> Result<(), io::Error> {
         buf.reserve(data.len());
-        buf.put_slice(&data);
+        buf.put_slice(data);
         Ok(())
     }
 }