![NSObject.mm
+ (BOOL)isKindOfClass:(Class)cls {
for (Class tcls = object_getClass((id)self); tcls; tcls = tcls->superclass) {
if (tcls == cls) return YES;
}
return NO;
}
- (BOOL)respondsToSelector:(SEL)sel {
if (!sel) return NO;
return class_respondsToSelector_inst([self class], sel, self);
}
- (BOOL)conformsToProtocol:(Protocol *)protocol {
if (!protocol) return NO;
for (Class tcls = [self class]; tcls; tcls = tcls->superclass) {
if (class_conformsToProtocol(tcls, protocol)) return YES;
}
return NO;
}
- (id)performSelector:(SEL)sel {
if (!sel) [self doesNotRecognizeSelector:sel];
return ((id(*)(id, SEL))objc_msgSend)(self, sel);
}](https://image.slidesharecdn.com/objective-cruntime-170530141220/85/Objective-c-Runtime-5-320.jpg)
![NSString *result = [example execWithParam:@"param"];
id objc_msgSend(id self, SEL op, ...)
result = objc_msgSend(example, @selector(execWithParam:), @"param");
Tail-call: typedef id (*IMP)(id self,SEL _cmd,...);
void objc_msgSend(void /* id self, SEL op, ... */ )
NSString *result = ((NSString* (*)(id, SEL, NSString *))objc_msgSend)(example,
@selector(execWithParam:), @"param");
Sending Messages](https://image.slidesharecdn.com/objective-cruntime-170530141220/85/Objective-c-Runtime-11-320.jpg)
![resolveInstanceMethod
1. Class cache -> class dispatch table -> all super classes
2. resolveInstanceMethod for @dynamic properties
id dynamicGetter(id self, SEL _cmd);
void dynamicSetter(id self, SEL _cmd, id value);
+ (BOOL)isDynamicProperty:(NSString *)selectorString;
+ (BOOL)resolveInstanceMethod:(SEL)sel {
NSString *selectorString = NSStringFromSelector(sel);
if ([self isDynamicProperty:selectorString]) {
if ([selectorString hasPrefix:@"set"]) {
class_addMethod(self, sel, (IMP)dynamicSetter, "v@:@");
} else {
class_addMethod(sel, sel, (IMP)dynamicGetter, "@@:");
}
return YES;
}
return [super resolveInstanceMethod:sel];
}
// "v@:@", "@@:" - Objective-C type encodings](https://image.slidesharecdn.com/objective-cruntime-170530141220/85/Objective-c-Runtime-14-320.jpg)
![forwardingTargetForSelector
3. The Runtime then calls forwardingTargetForSelector
Returns the object to which unrecognized messages should first be directed.
- (id)forwardingTargetForSelector:(SEL)aSelector {
if (aSelector == @selector(magicMethod:)) {
return magicObject;
} else {
return [super forwardingTargetForSelector:aSelector];
}
}](https://image.slidesharecdn.com/objective-cruntime-170530141220/85/Objective-c-Runtime-15-320.jpg)
![forwardInvocation
@implementation InvClass
- (NSString *)invWithFirst:(NSString *)first second:(NSNumber *)second
third:(NSArray *)third {
return [NSString stringWithFormat:@"first: %@, second: %@, third: %@", first, second,
third];
}
@end
// perform unrecognized selector
Example *example = [Example new];
SEL selector = @selector(invWithFirst:);
NSString *result = [example performSelector:selector
withObject:@"first"];](https://image.slidesharecdn.com/objective-cruntime-170530141220/85/Objective-c-Runtime-16-320.jpg)
![forwardInvocation
+ (BOOL)resolveInstanceMethod:(SEL)sel {
if (sel == @selector(invWithFirst:)) {
return NO;
}
return YES;
}
- (id)forwardingTargetForSelector:(SEL)aSelector {
if (aSelector == @selector(invWithFirst:)) {
return nil;
}
return [super forwardingTargetForSelector:aSelector];
}
- (NSMethodSignature *)methodSignatureForSelector:(SEL)aSelector {
NSMethodSignature* signature = [super methodSignatureForSelector:aSelector];
if (!signature) {
SEL customSelector = @selector(invWithFirst:second:third:);
signature = [_invObject methodSignatureForSelector:customSelector];
}
return signature;
}](https://image.slidesharecdn.com/objective-cruntime-170530141220/85/Objective-c-Runtime-17-320.jpg)
![forwardInvocation
- (void)forwardInvocation:(NSInvocation *)anInvocation {
SEL selector = anInvocation.selector;
if ([_invObject respondsToSelector:selector]) {
[anInvocation setTarget:_invObject];
SEL customSelector = @selector(invWithFirst:second:third:);
[anInvocation setSelector:customSelector];
NSString *first = @"first";
NSNumber *second = @2;
NSArray *third = @[@”3", @”33”, @”333"];
[anInvocation setArgument:&first atIndex:2];
[anInvocation setArgument:&second atIndex:3];
[anInvocation setArgument:&third atIndex:4];
[anInvocation invoke];
} else {
[self doesNotRecognizeSelector:selector];
}
}](https://image.slidesharecdn.com/objective-cruntime-170530141220/85/Objective-c-Runtime-18-320.jpg)
![#import <objc/runtime.h>
@import Crashlytics;
@implementation UIViewController (Tracking)
+ (void)load {
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
Class class = [self class];
SEL originalSelector = @selector(viewWillAppear:);
SEL swizzledSelector = @selector(swizzled_viewWillAppear:);
Method originalMethod = class_getInstanceMethod(class, originalSelector);
Method swizzledMethod = class_getInstanceMethod(class, swizzledSelector);
BOOL didAddMethod =
class_addMethod(class,
originalSelector,
method_getImplementation(swizzledMethod),
method_getTypeEncoding(swizzledMethod));
if (didAddMethod) {
class_replaceMethod(class,
swizzledSelector,
method_getImplementation(originalMethod),
method_getTypeEncoding(originalMethod));
} else {
method_exchangeImplementations(originalMethod, swizzledMethod);
}
});
}
- (void)swizzled_viewWillAppear:(BOOL)animated {
CLS_LOG(@"CLSLOG viewWillAppear: %@", self);
[self swizzled_viewWillAppear:animated];
}
@end](https://image.slidesharecdn.com/objective-cruntime-170530141220/85/Objective-c-Runtime-20-320.jpg)
Objective-c Runtime
- 1. The Objective-c Runtime Павел Альбицкий [email protected]
- 4. Adding Classes objc_allocateClassPair objc_disposeClassPair objc_registerClassPair objc_duplicateClass Instantiating Classes class_createInstance objc_constructInstance objc_destructInstance Working with Instances object_copy object_dispose object_setInstanceVariable object_getInstanceVariable object_getIndexedIvars object_getIvar object_setIvar object_getClassName object_getClass object_setClass Obtaining Class Definitions objc_getClassList objc_copyClassList objc_lookUpClass objc_getClass objc_getRequiredClass objc_getMetaClass Working with Instance Variables ivar_getName ivar_getTypeEncoding ivar_getOffset Associative References objc_setAssociatedObject objc_getAssociatedObject objc_removeAssociatedObjects
- 5. NSObject.mm + (BOOL)isKindOfClass:(Class)cls { for (Class tcls = object_getClass((id)self); tcls; tcls = tcls->superclass) { if (tcls == cls) return YES; } return NO; } - (BOOL)respondsToSelector:(SEL)sel { if (!sel) return NO; return class_respondsToSelector_inst([self class], sel, self); } - (BOOL)conformsToProtocol:(Protocol *)protocol { if (!protocol) return NO; for (Class tcls = [self class]; tcls; tcls = tcls->superclass) { if (class_conformsToProtocol(tcls, protocol)) return YES; } return NO; } - (id)performSelector:(SEL)sel { if (!sel) [self doesNotRecognizeSelector:sel]; return ((id(*)(id, SEL))objc_msgSend)(self, sel); }
- 6. NSObject @interface NSObject <NSObject> { Class isa; } typedef struct objc_class *Class; struct objc_class { Class isa; #if !__OBJC2__ Class super_class const char *name long version long info long instance_size struct objc_ivar_list *ivars struct objc_method_list **methodLists struct objc_cache *cache struct objc_protocol_list *protocols #endif };
- 7. NSObject typedef struct objc_object *id; typedef struct objc_selector *SEL; typedef struct objc_method *Method; typedef struct objc_ivar *Ivar; typedef struct objc_category *Category; typedef struct objc_property *objc_property_t; typedef struct objc_object Protocol;
- 8. Class hierarchy @interface BaseExample : NSObject { NSString *_ivarBase; } @property(nonatomic, strong) NSString *baseProperty; - (void)test; + (NSString *)baseClassMethod; @end #import "BaseExample.h" @interface Example : BaseExample { NSString *_ivarExample; } @property(nonatomic, strong) NSString *exampleProperty; - (void)test; - (NSString *)execWithParam:(NSString *)param; + (NSString *)exampleClassMethod; @end
- 9. Instance of Example Class Example Metaclass Example isa isa Class BaseExample isa Class NSObject isa Metaclass BaseExample Metaclass NSObject super_class super_class super_class super_class Class hierarchy
- 10. struct objc_method { SEL method_name; // signature of method char *method_types; // types of the parameters to the method IMP method_imp; // memory address of the start of code block }; typedef struct objc_method *Method; A selector is the name used to select a method to execute for an object, or the unique identifier that replaces the name when the source code is compiled. Selector – C-string; IMP - typedef id (*IMP)(id self,SEL _cmd,...); Method
- 11. NSString *result = [example execWithParam:@"param"]; id objc_msgSend(id self, SEL op, ...) result = objc_msgSend(example, @selector(execWithParam:), @"param"); Tail-call: typedef id (*IMP)(id self,SEL _cmd,...); void objc_msgSend(void /* id self, SEL op, ... */ ) NSString *result = ((NSString* (*)(id, SEL, NSString *))objc_msgSend)(example, @selector(execWithParam:), @"param"); Sending Messages
- 12. id objc_msgSend(id self, SEL op, ...) Sends a message with a simple return value to an instance of a class. double objc_msgSend_fpret(id self, SEL op, ...) Sends a message with a floating-point return value to an instance of a class. void objc_msgSend_stret(void * stretAddr, id theReceiver, SEL theSelector, ...) Sends a message with a data-structure return value to an instance of a class. id objc_msgSendSuper(struct objc_super *super, SEL op, ...) Sends a message with a simple return value to the superclass of an instance of a class. void objc_msgSendSuper_stret(struct objc_super *super, SEL op, ...) Sends a message with a data-structure return value to the superclass of an instance of a class. objc_msgSend
- 13. Message forwarding resolveInstanceMethod forwardingTargetForSelector forwardInvocation Message handled Message not handled Return NO Return YES Return nil Return replacement receiver
- 14. resolveInstanceMethod 1. Class cache -> class dispatch table -> all super classes 2. resolveInstanceMethod for @dynamic properties id dynamicGetter(id self, SEL _cmd); void dynamicSetter(id self, SEL _cmd, id value); + (BOOL)isDynamicProperty:(NSString *)selectorString; + (BOOL)resolveInstanceMethod:(SEL)sel { NSString *selectorString = NSStringFromSelector(sel); if ([self isDynamicProperty:selectorString]) { if ([selectorString hasPrefix:@"set"]) { class_addMethod(self, sel, (IMP)dynamicSetter, "v@:@"); } else { class_addMethod(sel, sel, (IMP)dynamicGetter, "@@:"); } return YES; } return [super resolveInstanceMethod:sel]; } // "v@:@", "@@:" - Objective-C type encodings
- 15. forwardingTargetForSelector 3. The Runtime then calls forwardingTargetForSelector Returns the object to which unrecognized messages should first be directed. - (id)forwardingTargetForSelector:(SEL)aSelector { if (aSelector == @selector(magicMethod:)) { return magicObject; } else { return [super forwardingTargetForSelector:aSelector]; } }
- 16. forwardInvocation @implementation InvClass - (NSString *)invWithFirst:(NSString *)first second:(NSNumber *)second third:(NSArray *)third { return [NSString stringWithFormat:@"first: %@, second: %@, third: %@", first, second, third]; } @end // perform unrecognized selector Example *example = [Example new]; SEL selector = @selector(invWithFirst:); NSString *result = [example performSelector:selector withObject:@"first"];
- 17. forwardInvocation + (BOOL)resolveInstanceMethod:(SEL)sel { if (sel == @selector(invWithFirst:)) { return NO; } return YES; } - (id)forwardingTargetForSelector:(SEL)aSelector { if (aSelector == @selector(invWithFirst:)) { return nil; } return [super forwardingTargetForSelector:aSelector]; } - (NSMethodSignature *)methodSignatureForSelector:(SEL)aSelector { NSMethodSignature* signature = [super methodSignatureForSelector:aSelector]; if (!signature) { SEL customSelector = @selector(invWithFirst:second:third:); signature = [_invObject methodSignatureForSelector:customSelector]; } return signature; }
- 18. forwardInvocation - (void)forwardInvocation:(NSInvocation *)anInvocation { SEL selector = anInvocation.selector; if ([_invObject respondsToSelector:selector]) { [anInvocation setTarget:_invObject]; SEL customSelector = @selector(invWithFirst:second:third:); [anInvocation setSelector:customSelector]; NSString *first = @"first"; NSNumber *second = @2; NSArray *third = @[@”3", @”33”, @”333"]; [anInvocation setArgument:&first atIndex:2]; [anInvocation setArgument:&second atIndex:3]; [anInvocation setArgument:&third atIndex:4]; [anInvocation invoke]; } else { [self doesNotRecognizeSelector:selector]; } }
- 19. Method Swizzling
- 20. #import <objc/runtime.h> @import Crashlytics; @implementation UIViewController (Tracking) + (void)load { static dispatch_once_t onceToken; dispatch_once(&onceToken, ^{ Class class = [self class]; SEL originalSelector = @selector(viewWillAppear:); SEL swizzledSelector = @selector(swizzled_viewWillAppear:); Method originalMethod = class_getInstanceMethod(class, originalSelector); Method swizzledMethod = class_getInstanceMethod(class, swizzledSelector); BOOL didAddMethod = class_addMethod(class, originalSelector, method_getImplementation(swizzledMethod), method_getTypeEncoding(swizzledMethod)); if (didAddMethod) { class_replaceMethod(class, swizzledSelector, method_getImplementation(originalMethod), method_getTypeEncoding(originalMethod)); } else { method_exchangeImplementations(originalMethod, swizzledMethod); } }); } - (void)swizzled_viewWillAppear:(BOOL)animated { CLS_LOG(@"CLSLOG viewWillAppear: %@", self); [self swizzled_viewWillAppear:animated]; } @end
- 21. URLs • Mike Ash • Objective-C Runtime Reference • Objective-C Runtime Programming Guide • opensource.apple.com
- 22. Спасибо за внимание! Павел Альбицкий [email protected]