1.使用消息發送機制創建對象，給對象發送消息
導入 #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里面設置 輸入msg修改為NO不檢測調用方法是用運行時,蘋果不建議直接使用objc_message來發送消息
2. runTime方法交換的使用
#import "NSURL+NewRequestUrl.h" //URL分類
#import <objc/runtime.h>
@implementation NSURL (NewRequestUrl)
//當項目所有.m文件裝載到內存優先執行load里面的指令，所以app啟動之前就已經執行了load
+(void) load{
// Method instanceMethod = class_getInstanceMethod([<#Class _Nullable __unsafe_unretained cls#>], <#SEL _Nonnull name#>)//對象方法
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為nil");
}
return url;
}
@end
//app已經入這個控制器，調用URLWithString方法時，就交換,最大的好處如果原工程相同方法比較多，又需要修改，可以不改變原工程的這些方法法，新增一個方法，避免去過多修改別人代碼導致混亂，直接修改全局，減少工作量！
- (void)viewDidLoad {
[super viewDidLoad];
/**
oc: 方法實質上就是 Sel指針指向 ---> IMP指針 --->IMP指向具體的方法實現代碼
*/
NSURL * url = [NSURL URLWithString:@"http://www.baidu.com百度"];
NSURLRequest * request = [NSURLRequest requestWithURL:url];
NSLog(@"%@",request);
}
3. KVO本質其實也是runtime
#import "ViewController.h"
#import "Person.h"
@interface ViewController ()
@end
@implementation ViewController{
Person * p;
}
- (void)viewDidLoad {
[super viewDidLoad];
//KVO 底層原理也是應用運行時
p =[[Person alloc] init];
//1.動態創建Person子類（NSKVONotyfing_person）2.改變p對象的類型為(NSKVONotyfing_person)
[p addObserver:self forKeyPath:@"name" options:NSKeyValueObservingOptionNew context:nil];
}
//KVO是對象屬性的setter方法監聽，所以對 對象的成員屬性的監聽是不會走 -(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";
}
// 切記切記：在使用了鍵值觀察者模式一定要在移除，不然會發生崩潰
-(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調用根據添加觀察者時設置的NSKeyValueObservingOptionNew(改變以后在調用)值 NSKeyValueObservingOptionOld(改變之前調用)
[self willChangeValueForKey:name];
[super setName:name];
[self didChangeValueForKey:name];
}
@end
屏幕快照 2018-03-08 下午3.37.52.png
