diff --git a/internal/graphicsdriver/metal/ca/ca.go b/internal/graphicsdriver/metal/ca/ca.go
index 30f44aae5..7aeb06c13 100644
--- a/internal/graphicsdriver/metal/ca/ca.go
+++ b/internal/graphicsdriver/metal/ca/ca.go
@@ -31,7 +31,8 @@ import (
 // Suppress the warnings about availability guard with -Wno-unguarded-availability-new.
 // It is because old Xcode (8 or older?) does not accept @available syntax.
 
-// #cgo CFLAGS: -mmacosx-version-min=10.11 -Wno-unguarded-availability-new
+// #cgo CFLAGS: -Wno-unguarded-availability-new
+// #cgo !ios CFLAGS: -mmacosx-version-min=10.11
 // #cgo LDFLAGS: -framework QuartzCore -framework Foundation -framework CoreGraphics
 //
 // #include "ca.h"
diff --git a/internal/graphicsdriver/metal/ca/ca.h b/internal/graphicsdriver/metal/ca/ca.h
index 4190a41f2..5ce003069 100644
--- a/internal/graphicsdriver/metal/ca/ca.h
+++ b/internal/graphicsdriver/metal/ca/ca.h
@@ -14,9 +14,9 @@
 
 // +build darwin
 
-typedef signed char BOOL;
+#include <stdint.h>
+
 typedef unsigned long uint_t;
-typedef unsigned short uint16_t;
 
 void *MakeMetalLayer();
 
@@ -26,7 +26,7 @@ const char *MetalLayer_SetPixelFormat(void *metalLayer, uint16_t pixelFormat);
 const char *MetalLayer_SetMaximumDrawableCount(void *metalLayer,
                                                uint_t maximumDrawableCount);
 void MetalLayer_SetDisplaySyncEnabled(void *metalLayer,
-                                      BOOL displaySyncEnabled);
+                                      uint8_t displaySyncEnabled);
 void MetalLayer_SetDrawableSize(void *metalLayer, double width, double height);
 void *MetalLayer_NextDrawable(void *metalLayer);
 
diff --git a/internal/graphicsdriver/metal/ca/ca.m b/internal/graphicsdriver/metal/ca/ca.m
index b168c8d18..bbc1b79fe 100644
--- a/internal/graphicsdriver/metal/ca/ca.m
+++ b/internal/graphicsdriver/metal/ca/ca.m
@@ -20,10 +20,13 @@
 void *MakeMetalLayer() {
   CAMetalLayer *layer = [[CAMetalLayer alloc] init];
   // TODO: Expose a function to set color space.
+  // TODO: Enable colorspace on iOS: this will be available as of iOS 13.0.
+#if !TARGET_OS_IPHONE
   CGColorSpaceRef colorspace =
-      CGColorSpaceCreateWithName(kCGColorSpaceDisplayP3);
+    CGColorSpaceCreateWithName(kCGColorSpaceDisplayP3);
   layer.colorspace = colorspace;
   CGColorSpaceRelease(colorspace);
+#endif
   return layer;
 }
 
@@ -65,17 +68,19 @@ const char *MetalLayer_SetMaximumDrawableCount(void *metalLayer,
 }
 
 void MetalLayer_SetDisplaySyncEnabled(void *metalLayer,
-                                      BOOL displaySyncEnabled) {
+                                      uint8_t displaySyncEnabled) {
   // @available syntax is not available for old Xcode (#781)
   //
   // If possible, we'd want to write the guard like:
   //
   //     if (@available(macOS 10.13, *)) { ...
 
+#if !TARGET_OS_IPHONE
   if ([(CAMetalLayer *)metalLayer
           respondsToSelector:@selector(setDisplaySyncEnabled:)]) {
     [((CAMetalLayer *)metalLayer) setDisplaySyncEnabled:displaySyncEnabled];
   }
+#endif
 }
 
 void MetalLayer_SetDrawableSize(void *metalLayer, double width, double height) {
diff --git a/internal/graphicsdriver/metal/driver.go b/internal/graphicsdriver/metal/driver.go
index 3679d4f45..471d768bf 100644
--- a/internal/graphicsdriver/metal/driver.go
+++ b/internal/graphicsdriver/metal/driver.go
@@ -29,7 +29,8 @@ import (
 	"github.com/hajimehoshi/ebiten/internal/thread"
 )
 
-// #cgo CFLAGS: -x objective-c -mmacosx-version-min=10.11
+// #cgo CFLAGS: -x objective-c
+// #cgo !ios CFLAGS: -mmacosx-version-min=10.11
 // #cgo LDFLAGS: -framework Foundation
 //
 // #import <Foundation/Foundation.h>
diff --git a/internal/graphicsdriver/metal/mtl/mtl.go b/internal/graphicsdriver/metal/mtl/mtl.go
index a0307ddd0..a8e53a7d8 100644
--- a/internal/graphicsdriver/metal/mtl/mtl.go
+++ b/internal/graphicsdriver/metal/mtl/mtl.go
@@ -30,7 +30,7 @@ import (
 	"unsafe"
 )
 
-// #cgo CFLAGS: -mmacosx-version-min=10.11
+// #cgo !ios CFLAGS: -mmacosx-version-min=10.11
 // #cgo LDFLAGS: -framework Metal -framework Foundation
 //
 // #include <stdlib.h>
@@ -437,16 +437,16 @@ func (d Device) MakeLibrary(source string, opt CompileOptions) (Library, error)
 //
 // Reference: https://developer.apple.com/documentation/metal/mtldevice/1433369-makerenderpipelinestate.
 func (d Device) MakeRenderPipelineState(rpd RenderPipelineDescriptor) (RenderPipelineState, error) {
-	blendingEnabled := C.BOOL(0)
+	blendingEnabled := 0
 	if rpd.ColorAttachments[0].BlendingEnabled {
-		blendingEnabled = C.BOOL(1)
+		blendingEnabled = 1
 	}
 	c := &rpd.ColorAttachments[0]
 	descriptor := C.struct_RenderPipelineDescriptor{
 		VertexFunction:                              rpd.VertexFunction.function,
 		FragmentFunction:                            rpd.FragmentFunction.function,
 		ColorAttachment0PixelFormat:                 C.uint16_t(c.PixelFormat),
-		ColorAttachment0BlendingEnabled:             C.BOOL(blendingEnabled),
+		ColorAttachment0BlendingEnabled:             C.uint8_t(blendingEnabled),
 		ColorAttachment0DestinationAlphaBlendFactor: C.uint8_t(c.DestinationAlphaBlendFactor),
 		ColorAttachment0DestinationRGBBlendFactor:   C.uint8_t(c.DestinationRGBBlendFactor),
 		ColorAttachment0SourceAlphaBlendFactor:      C.uint8_t(c.SourceAlphaBlendFactor),
diff --git a/internal/graphicsdriver/metal/mtl/mtl.h b/internal/graphicsdriver/metal/mtl/mtl.h
index eb7fccc12..159a0af11 100644
--- a/internal/graphicsdriver/metal/mtl/mtl.h
+++ b/internal/graphicsdriver/metal/mtl/mtl.h
@@ -15,18 +15,15 @@
 // +build darwin
 
 #include <stddef.h>
+#include <stdint.h>
 
-typedef signed char BOOL;
 typedef unsigned long uint_t;
-typedef unsigned char uint8_t;
-typedef unsigned short uint16_t;
-typedef unsigned long long uint64_t;
 
 struct Device {
   void *Device;
-  BOOL Headless;
-  BOOL LowPower;
-  BOOL Removable;
+  uint8_t Headless;
+  uint8_t LowPower;
+  uint8_t Removable;
   uint64_t RegistryID;
   const char *Name;
 };
@@ -45,7 +42,7 @@ struct RenderPipelineDescriptor {
   void *VertexFunction;
   void *FragmentFunction;
   uint16_t ColorAttachment0PixelFormat;
-  BOOL ColorAttachment0BlendingEnabled;
+  uint8_t ColorAttachment0BlendingEnabled;
   uint8_t ColorAttachment0DestinationAlphaBlendFactor;
   uint8_t ColorAttachment0DestinationRGBBlendFactor;
   uint8_t ColorAttachment0SourceAlphaBlendFactor;
@@ -108,7 +105,7 @@ struct Viewport {
 struct Device CreateSystemDefaultDevice();
 struct Devices CopyAllDevices();
 
-BOOL Device_SupportsFeatureSet(void *device, uint16_t featureSet);
+uint8_t Device_SupportsFeatureSet(void *device, uint16_t featureSet);
 void *Device_MakeCommandQueue(void *device);
 struct Library Device_MakeLibrary(void *device, const char *source,
                                   size_t sourceLength);
diff --git a/internal/graphicsdriver/metal/mtl/mtl.m b/internal/graphicsdriver/metal/mtl/mtl.m
index 49b9c3996..4315dede4 100644
--- a/internal/graphicsdriver/metal/mtl/mtl.m
+++ b/internal/graphicsdriver/metal/mtl/mtl.m
@@ -28,13 +28,18 @@ struct Device CreateSystemDefaultDevice() {
 
   struct Device d;
   d.Device = device;
+#if !TARGET_OS_IPHONE
   d.Headless = device.headless;
   d.LowPower = device.lowPower;
+#else
+  d.Headless = 0;
+  d.LowPower = 0;
+#endif
   d.Name = device.name.UTF8String;
   return d;
 }
 
-BOOL Device_SupportsFeatureSet(void *device, uint16_t featureSet) {
+uint8_t Device_SupportsFeatureSet(void *device, uint16_t featureSet) {
   return [(id<MTLDevice>)device supportsFeatureSet:featureSet];
 }
 
@@ -257,17 +262,21 @@ void RenderCommandEncoder_DrawIndexedPrimitives(
 }
 
 void BlitCommandEncoder_Synchronize(void *blitCommandEncoder, void *resource) {
+#if !TARGET_OS_IPHONE
   [(id<MTLBlitCommandEncoder>)blitCommandEncoder
       synchronizeResource:(id<MTLResource>)resource];
+#endif
 }
 
 void BlitCommandEncoder_SynchronizeTexture(void *blitCommandEncoder,
                                            void *texture, uint_t slice,
                                            uint_t level) {
+#if !TARGET_OS_IPHONE
   [(id<MTLBlitCommandEncoder>)blitCommandEncoder
       synchronizeTexture:(id<MTLTexture>)texture
                    slice:(NSUInteger)slice
                    level:(NSUInteger)level];
+#endif
 }
 
 void *Library_MakeFunction(void *library, const char *name) {
diff --git a/internal/graphicsdriver/metal/ns/ns.go b/internal/graphicsdriver/metal/ns/ns.go
index ee044dadb..3e7332000 100644
--- a/internal/graphicsdriver/metal/ns/ns.go
+++ b/internal/graphicsdriver/metal/ns/ns.go
@@ -27,7 +27,7 @@ import (
 	"github.com/hajimehoshi/ebiten/internal/graphicsdriver/metal/ca"
 )
 
-// #cgo CFLAGS: -mmacosx-version-min=10.11
+// #cgo !ios CFLAGS: -mmacosx-version-min=10.11
 //
 // #include "ns.h"
 import "C"