iOS运行时(4)——常用函数

1 类

1.1 创建对象

 id class_createInstance(Class cls, size_t extraBytes)

eg:

size_t size = class_getInstanceSize([Person class]);
Person *person = class_createInstance([Person class], size);

1.2 获取类名

const char *class_getName(Class cls) 

eg

const char *name = class_getName([Person class])

1.3 获取父类

Class class_getSuperclass(Class cls)

eg

Class class = class_getSuperclass([Person class]);

1.4 获取类的大小

size_t class_getInstanceSize(Class cls)

2 成员变量

2.1获取成员列表

Ivar *class_copyIvarList(Class cls, unsigned int *outCount)

eg:

  unsigned int count;
  Ivar *ivarList = class_copyIvarList([self class], &count);
  for (int i = 0; i < count; i++) {
      Ivar ivar = ivarList[i];
      // 获取成员属性名
      NSString *name = [NSString stringWithUTF8String:ivar_getName(ivar)];
      NSString *type = [NSString stringWithUTF8String:ivar_getTypeEncoding(ivar)];
      NSLog(@"%@%@", type, name);
  }

3 属性

3.1 获取成员列表

objc_property_t *class_copyPropertyList(Class cls, unsigned int *outCount)

eg:

  unsigned int count;
  objc_property_t *propertyList = class_copyPropertyList([self class], &count);
  for (int i = 0; i < count; i++) {
      objc_property_t property = propertyList[i];
      // 获取成员属性名
      NSString *name = [NSString stringWithUTF8String:property_getName(property)];
      NSString *type = [NSString stringWithUTF8String:property_getAttributes(property)];
      NSLog(@"%@%@", type, name);
  }

4 方法

4.1 获取实例对象的方法

Method class_getInstanceMethod(Class cls, SEL name)

eg

Method method = class_getInstanceMethod([self class], @selector(methodName));

4.2 获取类的方法

Method class_getClassMethod(Class cls, SEL name)

eg

Method method = class_getClassMethod([self class], @selector(methodName));

4.3 获取方法的函数指针(IMP)

IMP class_getMethodImplementation(Class cls, SEL name)

eg:

IMP imp = class_getMethodImplementation([self class], @selector(methodName));

4.4获取方法列表

Method *class_copyMethodList(Class cls, unsigned int *outCount)

 unsigned int count;
  Method *methodList = class_copyMethodList([self class], &count);
  for (int i = 0; i < count; i++) {
      Method method = methodList[i];
      NSLog(@"%s%s", __func__, sel_getName(method_getName(method)));
  }

4.5增加方法

BOOL class_addMethod(Class cls, SEL name, IMP imp, const char *types)

 class_addMethod(theClass, selector,  method_getImplementation(method),  method_getTypeEncoding(method));

4.6方法替换

IMP class_replaceMethod(Class cls, SEL name, IMP imp, 
                                    const char *types) 

 class_replaceMethod(class, swizzledSelector, method_getImplementation(originalMethod), method_getTypeEncoding(originalMethod));

4.7 方法交换

+ (void)load {
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        Class class = [self class];

        SEL originalSelector = @selector(viewWillAppear:);
        SEL swizzledSelector = @selector(bx_viewWillAppear:);

        Method originalMethod = class_getInstanceMethod(class, originalSelector);
        Method swizzledMethod = class_getInstanceMethod(class, swizzledSelector);

        BOOL success = class_addMethod(class, originalSelector, method_getImplementation(swizzledMethod), method_getTypeEncoding(swizzledMethod));
        if (success) {
            class_replaceMethod(class, swizzledSelector, method_getImplementation(originalMethod), method_getTypeEncoding(originalMethod));
        } else {
            method_exchangeImplementations(originalMethod, swizzledMethod);
        }
    });
}