Merge pull request #2 from HaloWang/master - perfect message forward

Tuccuay · Apr 29, 2016 · 021428f · 021428f
1 parent 5e8fba9
commit 021428f
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Showing 4 changed files with 103 additions and 30 deletions.
diff --git a/ForwardMessage/Base.lproj/Main.storyboard b/ForwardMessage/Base.lproj/Main.storyboard
@@ -1,25 +1,62 @@
 <?xml version="1.0" encoding="UTF-8" standalone="no"?>
-<document type="com.apple.InterfaceBuilder3.CocoaTouch.Storyboard.XIB" version="3.0" toolsVersion="6211" systemVersion="14A298i" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES" useTraitCollections="YES" initialViewController="BYZ-38-t0r">
+<document type="com.apple.InterfaceBuilder3.CocoaTouch.Storyboard.XIB" version="3.0" toolsVersion="10116" systemVersion="15E65" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES" useTraitCollections="YES" initialViewController="jKV-aG-N9G">
     <dependencies>
-        <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="6204"/>
+        <deployment identifier="iOS"/>
+        <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="10085"/>
     </dependencies>
     <scenes>
         <!--View Controller-->
         <scene sceneID="tne-QT-ifu">
             <objects>
-                <viewController id="BYZ-38-t0r" customClass="ViewController" customModuleProvider="" sceneMemberID="viewController">
+                <viewController id="BYZ-38-t0r" customClass="ViewController" sceneMemberID="viewController">
                     <layoutGuides>
                         <viewControllerLayoutGuide type="top" id="y3c-jy-aDJ"/>
                         <viewControllerLayoutGuide type="bottom" id="wfy-db-euE"/>
                     </layoutGuides>
                     <view key="view" contentMode="scaleToFill" id="8bC-Xf-vdC">
                         <rect key="frame" x="0.0" y="0.0" width="600" height="600"/>
                         <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
+                        <subviews>
+                            <button opaque="NO" contentMode="scaleToFill" fixedFrame="YES" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="roundedRect" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="L2J-GH-GVP">
+                                <rect key="frame" x="20" y="72" width="60" height="30"/>
+                                <state key="normal" title="实例方法"/>
+                                <connections>
+                                    <action selector="instanceMethodCalling" destination="BYZ-38-t0r" eventType="touchUpInside" id="alc-pL-IYP"/>
+                                </connections>
+                            </button>
+                            <button opaque="NO" contentMode="scaleToFill" fixedFrame="YES" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="roundedRect" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="qn3-Fc-vBe">
+                                <rect key="frame" x="21" y="110" width="45" height="30"/>
+                                <state key="normal" title="类方法"/>
+                                <connections>
+                                    <action selector="classMethodCalling" destination="BYZ-38-t0r" eventType="touchUpInside" id="52K-o0-lvH"/>
+                                </connections>
+                            </button>
+                        </subviews>
                         <color key="backgroundColor" white="1" alpha="1" colorSpace="custom" customColorSpace="calibratedWhite"/>
                     </view>
+                    <navigationItem key="navigationItem" id="1yZ-bv-73P"/>
                 </viewController>
                 <placeholder placeholderIdentifier="IBFirstResponder" id="dkx-z0-nzr" sceneMemberID="firstResponder"/>
             </objects>
+            <point key="canvasLocation" x="816" y="-370"/>
+        </scene>
+        <!--Navigation Controller-->
+        <scene sceneID="yrP-D4-I2P">
+            <objects>
+                <navigationController automaticallyAdjustsScrollViewInsets="NO" id="jKV-aG-N9G" sceneMemberID="viewController">
+                    <toolbarItems/>
+                    <navigationBar key="navigationBar" contentMode="scaleToFill" id="09b-gs-mYv">
+                        <rect key="frame" x="0.0" y="0.0" width="320" height="44"/>
+                        <autoresizingMask key="autoresizingMask"/>
+                    </navigationBar>
+                    <nil name="viewControllers"/>
+                    <connections>
+                        <segue destination="BYZ-38-t0r" kind="relationship" relationship="rootViewController" id="JMK-d5-cAu"/>
+                    </connections>
+                </navigationController>
+                <placeholder placeholderIdentifier="IBFirstResponder" id="LaK-zr-J3m" userLabel="First Responder" sceneMemberID="firstResponder"/>
+            </objects>
+            <point key="canvasLocation" x="129" y="-370"/>
         </scene>
     </scenes>
 </document>
diff --git a/ForwardMessage/Cat.h b/ForwardMessage/Cat.h
@@ -12,4 +12,6 @@
 
 + (void)stoke;
 
+- (void)stoke;
+
 @end
diff --git a/ForwardMessage/Cat.m b/ForwardMessage/Cat.m
@@ -10,53 +10,89 @@
 
 @implementation Cat
 
-// 在没有找到方法时，会先调用此方法，可用于动态添加方法
-/*
+#pragma mark - 实例方法
+
+//  第一步
+//  在没有找到方法时，会先调用此方法，可用于动态添加方法
+//  返回 YES 表示相应 selector 的实现已经被找到并添加到了类中，否则返回 NO
+
 + (BOOL)resolveInstanceMethod:(SEL)sel {
-    return NO;
+    return YES;
 }
- */
 
-// 如果上面返回 NO，就会进入这一步，用于指定备选响应此 SEL 的对象
-// 如果返回 self 就会死循环
-/*
+//  第二步
+//  如果第一步的返回 NO 或者直接返回了 YES 而没有添加方法，该方法被调用
+//  在这个方法中，我们可以指定一个可以返回一个可以响应该方法的对象
+//  如果返回 self 就会死循环
+
 - (id)forwardingTargetForSelector:(SEL)aSelector {
     return nil;
 }
- */
 
-// 指定方法签名，若返回 nil，则不会进入下一步，而是无法处理消息
+//  第三步
+//  如果 `forwardingTargetForSelector:` 返回了 nil，则该方法会被调用，系统会询问我们要一个合法的『类型编码(Type Encoding)』
+//  https://developer.apple.com/library/mac/documentation/Cocoa/Conceptual/ObjCRuntimeGuide/Articles/ocrtTypeEncodings.html
+//  若返回 nil，则不会进入下一步，而是无法处理消息
+
 - (NSMethodSignature *)methodSignatureForSelector:(SEL)aSelector {
-    if ([NSStringFromSelector(aSelector) isEqualToString:@"stoke"]) {
-        return [NSMethodSignature signatureWithObjCTypes:"v@:"];
-    }
-
-    return [super methodSignatureForSelector:aSelector];
+    return [NSMethodSignature signatureWithObjCTypes:"v@:"];
 }
 
 // 当实现了此方法后，-doesNotRecognizeSelector: 将不会被调用
 // 如果要测试找不到方法，可以注释掉这一个方法
 // 在这里进行消息转发
 - (void)forwardInvocation:(NSInvocation *)anInvocation {
-
     // 我们还可以改变方法选择器
     [anInvocation setSelector:@selector(touch)];
     // 改变方法选择器后，还需要指定是哪个对象的方法
     [anInvocation invokeWithTarget:self];
 }
 
+- (void)touch {
+    NSLog(@"Cat 没有实现 -stoke 方法，并且成功的转成了 -touch 方法");
+}
+
 - (void)doesNotRecognizeSelector:(SEL)aSelector {
     NSLog(@"无法处理消息：%@", NSStringFromSelector(aSelector));
 }
 
-+ (void)touch {
-    NSLog(@"Cat 没有实现 stoke 方法，并且成功的转成了 touch 方法");
+#pragma mark - 类方法
+
+//  类方法也会直接消息转发机制
+//  不过有些东西可能会比较有趣：
+//  下述方法中：
+//  forwardingTargetForSelector
+//  methodSignatureForSelector
+//  forwardInvocation
+//  doesNotRecognizeSelector
+//  我们将前面的修饰符由 "-" 替换为了 "+"，
+//  但当我们在上述各个方法中的实现用调用 [super method] 时，method 的定义还是 NSObject 的实例方法
+//  这可能就和元类(MetaClass)相关了
+
+//  与 resolveInstanceMethod 相对应
++ (BOOL)resolveClassMethod:(SEL)sel {
+    return NO;
 }
 
-+ (void)stoke {
-    Cat *carson = [[Cat alloc] init];
-    [Cat performSelector:@selector(touch) withObject:nil afterDelay:0];
++ (id)forwardingTargetForSelector:(SEL)aSelector {
+    return nil;
 }
 
++ (NSMethodSignature *)methodSignatureForSelector:(SEL)aSelector {
+    return [NSMethodSignature signatureWithObjCTypes:"v@:"];
+}
+
++ (void)forwardInvocation:(NSInvocation *)anInvocation {
+    [anInvocation setSelector:@selector(touch)];
+    [anInvocation invokeWithTarget:self];
+}
+
++ (void)touch {
+    NSLog(@"Cat 没有实现 +stoke 方法，并且成功的转成了 +touch 方法");
+}
+
++ (void)doesNotRecognizeSelector:(SEL)aSelector {
+    NSLog(@"无法处理消息：%@", NSStringFromSelector(aSelector));
+}
 
 @end
diff --git a/ForwardMessage/ViewController.m b/ForwardMessage/ViewController.m
@@ -4,7 +4,6 @@
 // ForwardMessage / 消息转发
 
 #import "ViewController.h"
-
 #import "Cat.h"
 
 @interface ViewController ()
@@ -13,13 +12,12 @@ @interface ViewController ()
 
 @implementation ViewController
 
-- (void)viewDidLoad {
-    [super viewDidLoad];
-
+- (IBAction)instanceMethodCalling {
+    [[Cat new] stoke];
+}
+
+- (IBAction)classMethodCalling {
     [Cat stoke];
-
-    // 输出：
-    // 2016-04-24 00:27:12.823 ForwardMessage[50298:3350384] Cat 没有实现 stoke 方法，并且成功的转成了 touch 方法
 }
 
 @end