iOS

• 使用的自定义类，如下：

#import <Foundation/Foundation.h>

@interface Person : NSObject

@property(nonatomic,copy) NSString *name;
@property(nonatomic,copy) NSString *sex;
-(NSString *)sayName;
-(NSString *)saySex;

@end

• 动态变量控制

- (void)viewDidLoad {
    [super viewDidLoad];
    
    self.person = [Person new];
    _person.name = @"xiaoming";
    NSLog(@"XiaoMing first answer is %@",self.person.name);
    
    [self sayName];
}

- (void)sayName
{
    unsigned int count = 0;
    Ivar *ivar = class_copyIvarList([self.person class], &count);
    for (int i = 0; i<count; i++) {
        Ivar var = ivar[i];
        const char *varName = ivar_getName(var);
        NSString *proname = [NSString stringWithUTF8String:varName];
        
        if ([proname isEqualToString:@"_name"]) {   //这里别忘了给属性加下划线
            object_setIvar(self.person, var, @"daming");
            break;
        }
    }
    NSLog(@"XiaoMing change name  is %@",self.person.name);
}

• 动态添加方法

- (void)viewDidLoad {
    [super viewDidLoad];
    self.person = [Person new];
    [self sayFrom];
}

- (void)sayFrom
{
    class_addMethod([self.person class], @selector(guess), (IMP)guessAnswer, "v@:");
    if ([self.person respondsToSelector:@selector(guess)]) {
        //Method method = class_getInstanceMethod([self.xiaoMing class], @selector(guess));
        [self.person performSelector:@selector(guess)];
        
    } else{
        NSLog(@"Sorry,I don't know");
    }
}

void guessAnswer(id self,SEL _cmd){
    NSLog(@"function: guessAnswer");
    NSLog(@"__%@__", NSStringFromSelector(_cmd));
}

- (void) guess{
    NSLog(@"function: guess");
    NSLog(@"__%@__", NSStringFromSelector(_cmd));
}

• 动态交换两个方法的实现

- (void)viewDidLoad {
    [super viewDidLoad];
    self.person = [Person new];
    
    NSLog(@"%@",_person.sayName);
    NSLog(@"%@",_person.saySex);
    
    Method m1 = class_getInstanceMethod([self.person class], @selector(sayName));
    Method m2 = class_getInstanceMethod([self.person class], @selector(saySex));
  
    method_exchangeImplementations(m1, m2);
}

• 拦截并替换方法

@interface Tool : NSObject

+ (instancetype)sharedManager;
- (NSString *)changeMethod;
- (void)addCount;

@end

#import "Tool.h"

@interface Tool ()

@property (nonatomic, assign) NSInteger count;

@end

@implementation Tool

+ (instancetype)sharedManager {
    static Tool *_sInstance;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        _sInstance = [[Tool alloc] init];
    });
    
    return _sInstance;
}

- (NSString *)changeMethod
{
    return @"haha,你的方法被我替换掉了";
}

- (void)addCount
{
    _count += 1;
    
    NSLog(@"点击次数------%ld", _count);
}

@end

- (void)viewDidLoad {
    [super viewDidLoad];
    
    //这里也可以使用 [self.person class],不过要先初始化
    Method m1 = class_getInstanceMethod([Person class], @selector(sayName));
    Method m2 = class_getInstanceMethod([Tool class], @selector(changeMethod));
    
    method_exchangeImplementations(m1, m2);
}

• 在方法上增加额外功能

@implementation FiveViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    
    self.view.backgroundColor = [UIColor whiteColor];
    UIButton *button = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    button.frame = CGRectMake(100, 100, 100, 100);
    [button setTitle:@"按钮" forState:UIControlStateNormal];
    [button addTarget:self action:@selector(ButtonClick) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:button];
}

- (void)ButtonClick
{
    NSLog(@"按钮被点击了");
}

@end

• 对runtime进行归纳总结，代码如下:

　　1、加载运行时头文件：

#import <objc/runtime.h>

　　2、具体实现代码：

/** 自定义类：MyObject */
//头文件
#import <Foundation/Foundation.h>

@interface MyObject : NSObject
@property(strong,nonatomic) NSString *string;
@property(strong,nonatomic) NSArray  *array;

- (void)method1;
- (void)method2;
- (void)classMethod1;
@end

//源文件
#import "MyObject.h"
#import <objc/runtime.h>
@interface MyObject (){
    NSInteger _instance1;
    NSString  *_instance2;
}

@property(assign,nonatomic) NSInteger intrger;
- (void)method3WithArge1:(NSInteger)arge1 arge2:(NSString *)arge2;
@end

@implementation MyObject

-(void)classMethod1{
}

- (void)method1{
    NSLog(@"cell Method1");
}

- (void)method2{
}

- (void)method3WithArge1:(NSInteger)arge1 arge2:(NSString *)arge2{
    NSLog(@"arge1 %ld arge2 %@",arge1,arge2);
}

+ (BOOL)resolveInstanceMethod:(SEL)sel{
    NSString *selector = NSStringFromSelector(sel);
    if ([selector isEqualToString:@"method1"]) {
        class_addMethod(self.class, @selector(method1), (IMP)functionForMethod1, "@:");
    }
    return [super resolveInstanceMethod:sel];
}

void functionForMethod1(id self,SEL _cmd){
    NSLog(@"%@ %p",self,_cmd);
}

- (instancetype)forwardingTargetForSelector:(SEL)aSelector{
    NSString *selector = NSStringFromSelector(aSelector);
    if([selector isEqualToString:@"method2"]){
　　//return;
    }
    return [super forwardingTargetForSelector:aSelector];
}

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

@end

/** 实现代码 */
#import <objc/runtime.h>

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
　　//1.类相关函数
　　//得到类名 ViewController
    NSLog(@"%s",class_getName([self class]));
　　//父类类名
　　//This is superClass 0x10f426da0  isa指针地址
    NSLog(@"This is superClass %p",class_getSuperclass([self class]));

　　//是否是元类
　　//Is MateClass 0
    NSLog(@"Is MateClass %d",class_isMetaClass([self class]));
　　//实例变量大小
　　//848
    size_t a =  class_getInstanceSize([self class]);
    NSLog(@"%ld",a);
    unsigned int outCount = 0;
    MyObject *objtect = [[MyObject alloc] init];
    Class cls = objtect.class;
    
    //类名
    NSLog(@"Class name %s",class_getName(cls));
    //父类名字
    NSLog(@"SuperClass name  %s",class_getName(class_getSuperclass(cls)));
    //是否元类
    NSLog(@"Is MetaClass %@",(class_isMetaClass(cls))?@"":@"NOT");
    //变量大小
    NSLog(@"MyObject size %ld",class_getInstanceSize(cls));
    //变量信息
    Ivar string = class_getInstanceVariable(cls, "_string");
 
    if (string != NULL) {
         NSLog(@"MyObject instance messge %s",ivar_getName(string));
    }
    // 属性操作
    objc_property_t *v = class_copyPropertyList(cls, &outCount);
    for (NSInteger i = 0; i< outCount; i++) {
        objc_property_t property = v[i];
        NSLog(@"property is %s ",property_getName(property));
    }
    free(v);
   
    //成员变量
    Ivar *vars = class_copyIvarList(cls, &outCount);
    for (NSInteger i =0; i< outCount; i++) {
        Ivar ivar = vars[i];
        NSLog(@"copyIvarList is %s is %ld",ivar_getName(ivar),i);
    }
     free(vars);
    //方法操作
    Method *methods = class_copyMethodList(cls, &outCount);
    for (NSInteger i =0; i< outCount; i++) {
        Method met = methods[i];
    #pragma clang diagnostic ignored"-Wformat"
        NSLog(@"Method is %s",method_getName(met));
    }
    free(methods);

    //  Format specifies type 'char *' but the argument has type 'SEL _Nonnull'
    // 获取方法名
    Method method = class_getInstanceMethod(cls,@selector(method1));
    NSLog(@"Method name is %s",method_getName(method));
    // 判断方法是否存在
     #pragma clang diagnostic ignored"-Wundeclared-selector"
    NSLog(@"Have you method %d",class_respondsToSelector(cls, @selector(method3WithArge1:arge2:)));
    // 指向函数实现的指针，相当于方法的实现
    IMP imp = class_getMethodImplementation(cls, @selector(method1));
    imp();
    //动态创建类
     #pragma clang diagnostic ignored" -Wunused-variable"
    // 注:运行时规定,只能在objc_allocateClassPair与objc_registerClassPair两个函数之间为类添加变量
    //  1.添加一个自定义的类 类名是MySubClass
    //  父类class,类名,额外空间
    Class myClass = objc_allocateClassPair(objtect.class, "MySubClass", 0);
    //  2.增加方法，交换方法
    //注:  v@: 意思是 v是void   @:没有返回参数
    if( class_addMethod(myClass, @selector(mysubMethod1),(IMP)mysubMethod1, "v@:")){
        class_replaceMethod(myClass, @selector(method1),  (IMP)mysubMethod1,"v@:");
    }

    /*
     3.增加一个NSSsting类型属性  属性名myString
    变量size sizeof(NSString)
    对齐     指针类型的为log2(sizeof(NSString*))
    类型     @encode(NSString*)
    class_addIvar(class,变量名,变量size,对齐,类型)
    */
    //添加同名属性会失败
    BOOL isd =  class_addIvar(myClass, "_myString", sizeof(NSString *),  log(sizeof(NSString *)), @encode(NSString *));
    NSLog(@"属性是否添加成功 %d",isd);
    /*
    特性相关编码
    属性的特性字符串 以 T@encode(type) 开头, 以 V实例变量名称 结尾,中间以特性编码填充,通过property_getAttributes即可查看
    特性编码 具体含义
    R readonly
    C copy
    & retain ARC strong
    N nonatomic
    G(name) getter=(name)
    S(name) setter=(name)
    D @dynamic
    W weak
    P 用于垃圾回收机制
    */
    //@T
    objc_property_attribute_t type;
    type.name = "T";
    type.value = @encode(NSString *);
    //copy
    objc_property_attribute_t owership = {"C",""};
    //nonatomic
    objc_property_attribute_t oeership2 = {"N",""};
    //V_属性名
    objc_property_attribute_t var = {"V","_myString"};
    //特性数组
    objc_property_attribute_t attributes[] = {type,owership,oeership2,var};
    //向类中添加名为myString的属性,属性的特性包含在attributes中
    class_addProperty(myClass, "myString", attributes, 4);
    unsigned int propertyCount;
    objc_property_t * properties = class_copyPropertyList(myClass, &propertyCount);
    for (int i = 0; i<propertyCount; i++) {
        NSLog(@"属性的名称为 : %s",property_getName(properties[i]));
        NSLog(@"属性的特性字符串为: %s",property_getAttributes(properties[i]));
    }
    //释放属性列表数组
    free(properties);
    
    //在应用中注册由objc_allocateClassPair创建的类
    objc_registerClassPair(myClass);
    
    id instance = [[myClass alloc] init];
    [instance performSelector:@selector(mysubMethod1)];
    [instance performSelector:@selector(method1)];
    
    // 销毁一个类及相关联的类
    // 不过需要注意的是，如果程序运行中还存在类或其子类的实例，则不能调用针对类调用该方法
    //objc_disposeClassPair(myClass);
    
    //关联对象
    UIView *view = [[UIView alloc] initWithFrame:CGRectMake(100, 100, 100, 100)];
    view.backgroundColor = [UIColor redColor];
    [view setTapActionWithBlock:^{
        NSLog(@"saAS");
    }];
    [self.view addSubview:view];
　　//SEL
　　//Objective-C在编译时，会依据每一个方法的名字、参数序列，生成一个唯一的整型标识(Int类型的地址)，这个标识就是SEL
　　//SEL只是一个指向方法的指针（准确的说，只是一个根据方法名hash化了的KEY值，能唯一代表一个方法
　　//而对于字符串的比较仅仅需要比较他们的地址就可以了，可以说速度上无语伦比
　　//sel : 0x104dd7735
    /*
    三种方法来获取SEL:
    
    sel_registerName函数
    Objective-C编译器提供的@selector()
    NSSelectorFromString()方法
    */

    SEL sel1 = @selector(method1);
    NSLog(@"sel : %p", sel1);
}

static void mysubMethod1(id self,SEL _cmd){
    NSLog(@"这是添加的方法");
}

@end