Implemented actual hooks and included new examples

ASHookIt.xcodeproj/project.pbxproj

@@ -14,6 +14,8 @@
 		6DCD89831E63676500F620D2 /* ASHook.m in Sources */ = {isa = PBXBuildFile; fileRef = 6DCD89811E63676500F620D2 /* ASHook.m */; };
 		6DCD89861E63678B00F620D2 /* ASHook+MethodSwizzler.h in Headers */ = {isa = PBXBuildFile; fileRef = 6DCD89841E63678B00F620D2 /* ASHook+MethodSwizzler.h */; settings = {ATTRIBUTES = (Public, ); }; };
 		6DCD89871E63678B00F620D2 /* ASHook+MethodSwizzler.m in Sources */ = {isa = PBXBuildFile; fileRef = 6DCD89851E63678B00F620D2 /* ASHook+MethodSwizzler.m */; };
+		6DCD898A1E636A2000F620D2 /* ASHook+BlockInsert.h in Headers */ = {isa = PBXBuildFile; fileRef = 6DCD89881E636A2000F620D2 /* ASHook+BlockInsert.h */; settings = {ATTRIBUTES = (Public, ); }; };
+		6DCD898B1E636A2000F620D2 /* ASHook+BlockInsert.m in Sources */ = {isa = PBXBuildFile; fileRef = 6DCD89891E636A2000F620D2 /* ASHook+BlockInsert.m */; };
 /* End PBXBuildFile section */
 
 /* Begin PBXContainerItemProxy section */
@@ -37,6 +39,8 @@
 		6DCD89811E63676500F620D2 /* ASHook.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = ASHook.m; sourceTree = "<group>"; };
 		6DCD89841E63678B00F620D2 /* ASHook+MethodSwizzler.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = "ASHook+MethodSwizzler.h"; sourceTree = "<group>"; };
 		6DCD89851E63678B00F620D2 /* ASHook+MethodSwizzler.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = "ASHook+MethodSwizzler.m"; sourceTree = "<group>"; };
+		6DCD89881E636A2000F620D2 /* ASHook+BlockInsert.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = "ASHook+BlockInsert.h"; sourceTree = "<group>"; };
+		6DCD89891E636A2000F620D2 /* ASHook+BlockInsert.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = "ASHook+BlockInsert.m"; sourceTree = "<group>"; };
 /* End PBXFileReference section */
 
 /* Begin PBXFrameworksBuildPhase section */
@@ -84,6 +88,8 @@
 				6DCD89811E63676500F620D2 /* ASHook.m */,
 				6DCD89841E63678B00F620D2 /* ASHook+MethodSwizzler.h */,
 				6DCD89851E63678B00F620D2 /* ASHook+MethodSwizzler.m */,
+				6DCD89881E636A2000F620D2 /* ASHook+BlockInsert.h */,
+				6DCD89891E636A2000F620D2 /* ASHook+BlockInsert.m */,
 				6DCD892F1E63091F00F620D2 /* Info.plist */,
 			);
 			path = ASHookIt;
@@ -105,9 +111,10 @@
 			isa = PBXHeadersBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
+				6DCD893C1E63091F00F620D2 /* ASHookIt.h in Headers */,
 				6DCD89821E63676500F620D2 /* ASHook.h in Headers */,
 				6DCD89861E63678B00F620D2 /* ASHook+MethodSwizzler.h in Headers */,
-				6DCD893C1E63091F00F620D2 /* ASHookIt.h in Headers */,
+				6DCD898A1E636A2000F620D2 /* ASHook+BlockInsert.h in Headers */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};
@@ -210,6 +217,7 @@
 			buildActionMask = 2147483647;
 			files = (
 				6DCD89871E63678B00F620D2 /* ASHook+MethodSwizzler.m in Sources */,
+				6DCD898B1E636A2000F620D2 /* ASHook+BlockInsert.m in Sources */,
 				6DCD89831E63676500F620D2 /* ASHook.m in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;

ASHookIt/ASHook+BlockInsert.h

@@ -0,0 +1,33 @@
+//
+//  ASHook+BlockInsert.h
+//  ASHookIt
+//
+//  Created by Adam Szedelyi on 2017. 02. 26..
+//  Copyright © 2017. Adam Szedelyi. All rights reserved.
+//
+
+#import <ASHookIt/ASHookIt.h>
+
+@interface ASHook (BlockInsert)
+
+/**
+ * Runs the given block on the target just before the given selector gets called.
+ *
+ * @param block The block that will run.
+ * @param targetInstance The instance where you want to run the block.
+ * @param originalSelector The original selector that will trigger the block and run after the block.
+ *
+ */
++ (void)runBlock:(void (^)(__unsafe_unretained id _self))block onTarget:(id)targetInstance beforeInstanceSelector:(SEL)originalSelector;
+
+/**
+ * Runs the given block on the target just before the given selector gets called.
+ *
+ * @param block The block that will run.
+ * @param targetClass The class where you want to run the block.
+ * @param originalSelector The original selector that will trigger the block and run after the block.
+ *
+ */
++ (void)runBlock:(void (^)(__unsafe_unretained id _self))block onTarget:(id)targetClass beforeClassSelector:(SEL)originalSelector;
+
+@end

ASHookIt/ASHook+BlockInsert.m

@@ -0,0 +1,73 @@
+//
+//  ASHook+BlockInsert.m
+//  ASHookIt
+//
+//  Created by Adam Szedelyi on 2017. 02. 26..
+//  Copyright © 2017. Adam Szedelyi. All rights reserved.
+//
+
+#import "ASHook+BlockInsert.h"
+#import "ASHook+MethodSwizzler.h"
+#import <objc/runtime.h>
+#import <objc/message.h>
+
+@interface ASHook ()
+
++ (void)swizzle:(id)target
+       selector:(SEL)originalSelector
+    newSelector:(SEL)newSelector
+ originalMethod:(Method)originalMethod
+      newMethod:(Method)newMethod;
+
+@end
+
+@implementation ASHook (BlockInsert)
+
+#pragma mark - Public methods
+
++ (void)runBlock:(void (^)(__unsafe_unretained id _self))block onTarget:(id)targetInstance beforeInstanceSelector:(SEL)originalSelector {
+    id target = [targetInstance class];
+    Method originalMethod = class_getInstanceMethod(target, originalSelector);
+    SEL newSelector = [self insertBlock:block onTarget:target originalSelector:originalSelector originalMethod:originalMethod];
+    if (newSelector) {
+        Method newMethod = class_getInstanceMethod(target, newSelector);
+        [ASHook swizzle:target selector:originalSelector newSelector:newSelector originalMethod:originalMethod newMethod:newMethod];
+    }
+}
+
++ (void)runBlock:(void (^)(__unsafe_unretained id _self))block onTarget:(id)targetClass beforeClassSelector:(SEL)originalSelector {
+    id target = object_getClass(targetClass);
+    Method originalMethod = class_getClassMethod(target, originalSelector);
+    SEL newSelector = [self insertBlock:block onTarget:target originalSelector:originalSelector originalMethod:originalMethod];
+    if (newSelector) {
+        Method newMethod = class_getClassMethod(target, newSelector);
+        [ASHook swizzle:target selector:originalSelector newSelector:newSelector originalMethod:originalMethod newMethod:newMethod];
+    }
+}
+
+#pragma mark - Private methods
+
+/*! @brief Creating and adding a new implementation for the original method with the block included. */
++ (SEL)insertBlock:(void (^)(__unsafe_unretained id _self))block
+          onTarget:(id)target
+originalSelector:(SEL)originalSelector
+  originalMethod:(Method)originalMethod {
+    NSString *swizzledMethodSuffix = @"_ASMethodSwizzled";
+    NSString *swizzledMethodName = [NSString stringWithFormat:@"%@%@", NSStringFromSelector(originalSelector), swizzledMethodSuffix];
+    SEL newSelector = NSSelectorFromString(swizzledMethodName);
+    id actionBlock = ^(__unsafe_unretained id _self) {
+        if (block != nil) {
+            block(_self);
+        }
+        ((void ( *)(id, SEL))objc_msgSend)(_self, newSelector); // Using ObjC messaging directly to avoid ARC messing with the lifecycle of the original object. (ie. had issues with some classes' dealloc otherwise)
+    };
+    IMP impl = imp_implementationWithBlock(actionBlock);
+    const char *encoding = method_getTypeEncoding(originalMethod);
+    if (!class_addMethod(target, newSelector, impl, encoding)) {
+        NSLog(@"Failed to add method: %@ on %@", NSStringFromSelector(newSelector), target);
+        return nil;
+    }
+    return newSelector;
+}
+
+@end

ASHookIt/ASHook+MethodSwizzler.m

@@ -15,7 +15,7 @@ @implementation ASHook (MethodSwizzler)
 #pragma mark - Public methods
 
 + (void)swizzle:(id)targetInstance instanceSelector:(SEL)originalSelector withInstanceSelector:(SEL)newSelector {
-    id target = object_getClass(targetInstance);
+    id target = [targetInstance class];
     Method originalMethod = class_getInstanceMethod(target, originalSelector);
     Method newMethod = class_getInstanceMethod(target, newSelector);
     [self swizzle:target selector:originalSelector newSelector:newSelector originalMethod:originalMethod newMethod:newMethod];

ASHookIt/ASHookIt.h

@@ -9,6 +9,7 @@
 #import <UIKit/UIKit.h>
 #import <ASHookIt/ASHook.h>
 #import <ASHookIt/ASHook+MethodSwizzler.h>
+#import <ASHookIt/ASHook+BlockInsert.h>
 
 //! Project version number for ASHookIt.
 FOUNDATION_EXPORT double ASHookItVersionNumber;

ASHookItDemo/ASHookItDemo/FirstViewController.m

@@ -18,23 +18,30 @@ @implementation FirstViewController
 #pragma mark - Swizzling example 1
 
 + (void)initialize {
-    // A simple class method swizzling example.
+    // Example 1: simple instance method swizzling
+    [ASHook swizzle:self instanceSelector:@selector(logHelloWorld) withInstanceSelector:@selector(logGoodbyeWorld)];
+
+    // Example 2: class method swizzling
     [ASHook swizzle:self classSelector:@selector(alloc) withClassSelector:@selector(swizzledAlloc)];
+
+    // Example 3: an instance method hook (before it runs) - the scope can be even all UIViewController objects
+    [ASHook runBlock:^(__unsafe_unretained id _self) {
+        NSLog(@"viewDidLoad will be called on %@!", _self);
+    } onTarget:[UIViewController class] beforeInstanceSelector:@selector(viewDidLoad)];
+
+    // Example 4: a class method hook (before it runs)
+    [ASHook runBlock:^(__unsafe_unretained id _self) {
+        NSLog(@"alloc will run - will there be any funny messages in it?");
+    } onTarget:self beforeClassSelector:@selector(alloc)];
 }
 
 + (instancetype)swizzledAlloc {
     NSLog(@"Whoah! Swizzled allocation of this class is cool!");
     return [super alloc];
 }
 
-#pragma mark - Swizzling example 2
-
 - (void)viewDidLoad {
     [super viewDidLoad];
-
-    // A simple instance method swizzling example.
-    [ASHook swizzle:self instanceSelector:@selector(logHelloWorld) withInstanceSelector:@selector(logGoodbyeWorld)];
-
     [self logHelloWorld];
 }