#import <Foundation/Foundation.h>

#import "Human.h"

@interface Plane : NSObject

-(void)fly:(Human*)p;

-(int)fly1;

-(void)fly2:(Human*)p withBird:(NSString*)birdName;

@end

#import "Plane.h"

@implementation Plane

-(void)fly:(Human*)p{

NSLog(@"Fly with a guy whose information is \"%@\"", [p description]);

NSLog(@"fly......");

}

-(int)fly1{

NSLog(@"I can fly in Plane for fly1");

return 0;

}

-(void)fly2:(Human*)p withBird:(NSString*)birdName{

NSLog(@"Fly with a guy whose information is \"%@\"", [p description]);

NSLog(@"fly......bird:'%@'.", birdName);

}

@end

#import <Foundation/Foundation.h>

void dynamicMethod(id self, SEL _cmd, float height);

@interface Human : NSObject{

float _height;

}

@property(retain, nonatomic) NSString * name;

@property(readonly) float weight;

@property float height;

-(id) initWithWeight:(float)weight;

-(NSString*)description;

@end

#import <objc/runtime.h>

#import "Human.h"

#import "Plane.h"

void dynamicMethod(id self, SEL _cmd, float height){

NSLog(@"dynamicMethod:%@", NSStringFromSelector(_cmd));

// here is a question. how to implement the statements to assign the property of id(human.height);

// looks like the dynamic property is just for linkage.

// 当赋值发生时，由于动态函数的全局性，可以访问其他全局变量，对象。所以更像一种链接机制

}

@implementation Human

@synthesize name;

@synthesize weight;

@dynamic height;

-(id)initWithWeight:(float)w{

if(self=[super init]){

weight = w;

}

return self;

}

-(NSString*)description{

return [NSString stringWithFormat:@"The human whose name is \"%@\". weight is [%f]. height is [%f]",

self.name, self.weight, self.height];

}

-(float)height{

return _height;

}

-(void)fly2{

NSLog(@"yes I can fly in 2!");

}

+(BOOL)resolveInstanceMethod:(SEL)sel{

NSString* method = NSStringFromSelector(sel);

if([method isEqualToString:@"setHeight:"]){

class_addMethod([self class], sel, (IMP)dynamicMethod, "v@:f");

}

return [super resolveInstanceMethod:sel];

}

-(NSMethodSignature*)methodSignatureForSelector:(SEL)selector{

NSMethodSignature * signature = [super methodSignatureForSelector:selector];

if(!signature&&[NSStringFromSelector(selector) isEqualToString:@"fly"]){

//signature = [[self class] instanceMethodSignatureForSelector:@selector(fly2)];

SEL newSel = NSSelectorFromString(@"fly1"); //will ok.

// SEL newSel = NSSelectorFromString(@"fly:");//will ok.

// SEL newSel = NSSelectorFromString(@"fly2:withBird");//will wrong.

//这里返回的消息，必须符合以下条件之一：

//方法名相同

//输入参数相同

if([Plane instancesRespondToSelector:newSel]){

signature = [Plane instanceMethodSignatureForSelector:newSel];

}

}

return signature;

}

-(void)forwardInvocation:(NSInvocation *)anInvocation{

NSString * selName = NSStringFromSelector([anInvocation selector]);

NSMethodSignature * sig = [anInvocation methodSignature];

NSLog(@"the signature %@", [NSString stringWithCString:[sig methodReturnType] encoding:NSUTF8StringEncoding]);

if([selName isEqualToString:@"fly"]){

Plane * p = [[Plane alloc] init];

SEL newSel = NSSelectorFromString(@"fly:");

IMP imp = [p methodForSelector:newSel];

imp(p, newSel, self);

[p release];

}

}

-(void)dealloc{

[self setName:nil];

[super dealloc];

}

@end

#import <Foundation/Foundation.h>

#import <objc/runtime.h>

#import "Human.h"

#import "Plane.h"

int main (int argc, const char * argv[])

{

@autoreleasepool {

// insert code here...

Human * h = [[Human alloc] initWithWeight:17.3];

h.name=@"Chris";

h.height = 18.0;

NSLog(@"%@", [h description]);

[h fly];

[h release];

h=nil;