iOS开发中runtime常用的几种方法示例总结

// OC代码:
[Person coding];

//运行时 runtime 会将它转化成 C 语言的代码:
objc_msgSend(Person, @selector(coding));

// 遍历某个类所有的成员变量
class_copyIvarList

// 遍历某个类所有的方法
class_copyMethodList

// 获取指定名称的成员变量
class_getInstanceVariable

// 获取成员变量名
ivar_getName

// 获取成员变量类型编码
ivar_getTypeEncoding

// 获取某个对象成员变量的值
object_getIvar

// 设置某个对象成员变量的值
object_setIvar

// 给对象发送消息
objc_msgSend

 unsigned int count = 0;
 // 动态获取类中的所有属性(包括私有)
 Ivar *ivar = class_copyIvarList(_person.class, &count);
 // 遍历属性找到对应字段
 for (int i = 0; i < count; i ++) {
  Ivar tempIvar = ivar[i];
  const char *varChar = ivar_getName(tempIvar);
  NSString *varString = [NSString stringWithUTF8String:varChar];
  if ([varString isEqualToString:@"_name"]) {
   // 修改对应的字段值
   object_setIvar(_person, tempIvar, @"更改属性值成功");
   break;
  }
 }

- (void)setName:(NSString *)name {
 objc_setAssociatedObject(self, @"name", name, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}

- (NSString *)name {
 return objc_getAssociatedObject(self, @"name");
}

 NSObject *person = [NSObject new];
 person.name = @"以梦为马";

- (void)buttonClick:(UIButton *)sender {
 /*
  动态添加 coding 方法
  (IMP)codingOC 意思是 codingOC 的地址指针;
  "v@:" 意思是，v 代表无返回值 void，如果是 i 则代表 int；@代表 id sel; : 代表 SEL _cmd;
  “v@:@@” 意思是，两个参数的没有返回值。
  */
 class_addMethod([_person class], @selector(coding), (IMP)codingOC, "v@:");
 // 调用 coding 方法响应事件
 if ([_person respondsToSelector:@selector(coding)]) {
  [_person performSelector:@selector(coding)];
  self.testLabelText = @"添加方法成功";
 } else {
  self.testLabelText = @"添加方法失败";
 }
}

 
// 编写 codingOC 的实现
void codingOC(id self,SEL _cmd) {
 NSLog(@"添加方法成功");
}

 Method oriMethod = class_getInstanceMethod(_person.class, @selector(coding));
 Method curMethod = class_getInstanceMethod(_person.class, @selector(eating));
 method_exchangeImplementations(oriMethod, curMethod);

 _person = [NNPerson new];
 _library = [NNLibrary new];
 self.testLabelText = [_library libraryMethod];
 Method oriMethod = class_getInstanceMethod(_person.class, @selector(changeMethod));
 Method curMethod = class_getInstanceMethod(_library.class, @selector(libraryMethod));
 method_exchangeImplementations(oriMethod, curMethod);

+ (void)load {
 static dispatch_once_t onceToken;
 dispatch_once(&onceToken, ^{
  Method oriMethod = class_getInstanceMethod(self.class, @selector(sendAction:to:forEvent:));
  Method cusMethod = class_getInstanceMethod(self.class, @selector(customSendAction:to:forEvent:));
  // 判断自定义的方法是否实现, 避免崩溃
  BOOL addSuccess = class_addMethod(self.class, @selector(sendAction:to:forEvent:), method_getImplementation(cusMethod), method_getTypeEncoding(cusMethod));
  if (addSuccess) {
   // 没有实现, 将源方法的实现替换到交换方法的实现
   class_replaceMethod(self.class, @selector(customSendAction:to:forEvent:), method_getImplementation(oriMethod), method_getTypeEncoding(oriMethod));
  } else {
   // 已经实现, 直接交换方法
   method_exchangeImplementations(oriMethod, cusMethod);
  }
 });
}

- (void)encodeWithCoder:(NSCoder *)aCoder {
 unsigned int count = 0;
 // 获取类中所有属性
 Ivar *ivars = class_copyIvarList(self.class, &count);
 // 遍历属性
 for (int i = 0; i < count; i ++) {
  // 取出 i 位置对应的属性
  Ivar ivar = ivars[i];
  // 查看属性
  const char *name = ivar_getName(ivar);
  NSString *key = [NSString stringWithUTF8String:name];
  // 利用 KVC 进行取值，根据属性名称获取对应的值
  id value = [self valueForKey:key];
  [aCoder encodeObject:value forKey:key];
 }
 free(ivars);
}

- (instancetype)initWithCoder:(NSCoder *)aDecoder {
 if (self = [super init]) {
  unsigned int count = 0;
  // 获取类中所有属性
  Ivar *ivars = class_copyIvarList(self.class, &count);
  // 遍历属性
  for (int i = 0; i < count; i ++) {
   // 取出 i 位置对应的属性
   Ivar ivar = ivars[i];
   // 查看属性
   const char *name = ivar_getName(ivar);
   NSString *key = [NSString stringWithUTF8String:name];
   // 进行解档取值
   id value = [aDecoder decodeObjectForKey:key];
   // 利用 KVC 对属性赋值
   [self setValue:value forKey:key];
  }
 }
 return self;
}

/** 字典转模型 **/
+ (instancetype)modelWithDict:(NSDictionary *)dict {
 id objc = [[self alloc] init];
 unsigned int count = 0;
 // 获取成员属性数组
 Ivar *ivarList = class_copyIvarList(self, &count);
 // 遍历所有的成员属性名
 for (int i = 0; i < count; i ++) {
  // 获取成员属性
  Ivar ivar = ivarList[i];
  // 获取成员属性名
  NSString *ivarName = [NSString stringWithUTF8String:ivar_getName(ivar)];
  NSString *key = [ivarName substringFromIndex:1];
  // 从字典中取出对应 value 给模型属性赋值
  id value = dict[key];
  // 获取成员属性类型
  NSString *ivarType = [NSString stringWithUTF8String:ivar_getTypeEncoding(ivar)];
  // 判断 value 是不是字典
  if ([value isKindOfClass:[NSDictionary class]]) {
   ivarType = [ivarType stringByReplacingOccurrencesOfString:@"@" withString:@""];
   ivarType = [ivarType stringByReplacingOccurrencesOfString:@""" withString:@""];
   Class modalClass = NSClassFromString(ivarType);
   // 字典转模型
   if (modalClass) {
    // 字典转模型
    value = [modalClass modelWithDict:value];
   }
  }
  if ([value isKindOfClass:[NSArray class]]) {
   // 判断对应类有没有实现字典数组转模型数组的协议
   if ([self respondsToSelector:@selector(arrayContainModelClass)]) {
    // 转换成id类型，就能调用任何对象的方法
    id idSelf = self;
    // 获取数组中字典对应的模型
    NSString *type = [idSelf arrayContainModelClass][key];
    // 生成模型
    Class classModel = NSClassFromString(type);
    NSMutableArray *arrM = [NSMutableArray array];
    // 遍历字典数组，生成模型数组
    for (NSDictionary *dict in value) {
     // 字典转模型
     id model = [classModel modelWithDict:dict];
     [arrM addObject:model];
    }
    // 把模型数组赋值给value
    value = arrM;
   }
  }
  // KVC 字典转模型
  if (value) {
   [objc setValue:value forKey:key];
  }
 }
 return objc;
}