1.使用消息发送机制创建对象，给对象发送消息
导入 #import <objc/message.h>
/* - OC
Person * person = [Person new];
[person run];
*/
Person * person = objc_msgSend(objc_getClass("Person"), sel_registerName("alloc"));
objc_msgSend(person, sel_registerName("init"));
objc_msgSend(person, @selector(run));//需要在Build setting里面设置 输入msg修改为NO不检测调用方法是用运行时,苹果不建议直接使用objc_message来发送消息
2. runTime方法交换的使用
#import "NSURL+NewRequestUrl.h" //URL分类
#import <objc/runtime.h>
@implementation NSURL (NewRequestUrl)
//当项目所有.m文件装载到内存优先执行load里面的指令，所以app启动之前就已经执行了load
+(void) load{
// Method instanceMethod = class_getInstanceMethod([<#Class _Nullable __unsafe_unretained cls#>], <#SEL _Nonnull name#>)//对象方法
Method classSystemMethod = class_getClassMethod(self, @selector(URLWithString:));
Method classCustomMethod = class_getClassMethod(self, @selector(AwNewReqestUrlWithString:));
method_exchangeImplementations(classCustomMethod, classSystemMethod);
}
+(instancetype) AwNewReqestUrlWithString:(NSString *) urlSting{
NSURL * url = [NSURL AwNewReqestUrlWithString:urlSting];
if ([url isKindOfClass:[NSNull class]] || url == nil || url.description.length == 0) {
NSLog(@"url为nil");
}
return url;
}
@end
//app已经入这个控制器，调用URLWithString方法时，就交换,最大的好处如果原工程相同方法比较多，又需要修改，可以不改变原工程的这些方法法，新增一个方法，避免去过多修改别人代码导致混乱，直接修改全局，减少工作量！
- (void)viewDidLoad {
[super viewDidLoad];
/**
oc: 方法实质上就是 Sel指针指向 ---> IMP指针 --->IMP指向具体的方法实现代码
*/
NSURL * url = [NSURL URLWithString:@"http://www.baidu.com百度"];
NSURLRequest * request = [NSURLRequest requestWithURL:url];
NSLog(@"%@",request);
}
3. KVO本质其实也是runtime
#import "ViewController.h"
#import "Person.h"
@interface ViewController ()
@end
@implementation ViewController{
Person * p;
}
- (void)viewDidLoad {
[super viewDidLoad];
//KVO 底层原理也是应用运行时
p =[[Person alloc] init];
//1.动态创建Person子类（NSKVONotyfing_person）2.改变p对象的类型为(NSKVONotyfing_person)
[p addObserver:self forKeyPath:@"name" options:NSKeyValueObservingOptionNew context:nil];
}
//KVO是对象属性的setter方法监听，所以对 对象的成员属性的监听是不会走 -(void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary<NSKeyValueChangeKey,id> *)change context:(void *)context方法
-(void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary<NSKeyValueChangeKey,id> *)change context:(void *)context{
NSLog(@"%@---%@---%@",keyPath,object,change);
}
-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{
p.name = @"awuge";
}
// 切记切记：在使用了键值观察者模式一定要在移除，不然会发生崩溃
-(void)dealloc{
[p removeObserver:self forKeyPath:@"name"];
}
#import <Foundation/Foundation.h>
@interface Person : NSObject
@property(nonatomic,strong) NSString * name;
@end
-------------------
#import "Person.h"
@implementation Person
@end
#import "Person.h"
@interface NSKVONotyfing_person : Person
@end
-----------------------------------
#import "NSKVONotyfing_person.h"
@implementation NSKVONotyfing_person
-(void)setName:(NSString *)name{
//willChangeValueForKey和didChangeValueForKey调用根据添加观察者时设置的NSKeyValueObservingOptionNew(改变以后在调用)值 NSKeyValueObservingOptionOld(改变之前调用)
[self willChangeValueForKey:name];
[super setName:name];
[self didChangeValueForKey:name];
}
@end
屏幕快照 2018-03-08 下午3.37.52.png
