runtime简单学习2018-03-09

1动态改变属性

Person定义如下

@interface Person : NSObject

{

    NSString  *age;

}

@property(nonatomic,copy) NSString *name;

@property(nonatomic,copy) NSString *sex;

-(NSString *)sayName;

-(NSString *)saySex;

@end

下面是代码片段

self.person = [Person new];

_person.name = @"liju";

unsigned int count = 0;

objc_property_t *ivar = class_copyPropertyList([self.person class], &count);//仅仅是对象类的属性(@property申明的属性)

//这个遍历里面就访问不到age属性

动态增加方法

- (void)dynamicAddMethod

{

    class_addMethod([Person class], @selector(guess), class_getMethodImplementation([UIViewController class], @selector(guess)), "v@:");

    if ([self.person respondsToSelector:@selector(guess)]) {

        [self.person performSelector:@selector(guess)];//调用增加的方法

    } else{

        NSLog(@"无此方法");

    }

}

-(void)guess{

    NSLog(@"6666");

}

//动态增加属性的方法

- (void)addStrPropertyForTargetClass:(Class)targetClass Name:(NSString *)propertyName{

    objc_property_attribute_t type = { "T", [[NSString stringWithFormat:@"@\"%@\"",NSStringFromClass([NSString class])] UTF8String] }; //type

    objc_property_attribute_t ownership0 = { "C", "" }; // C = copy

    objc_property_attribute_t ownership = { "N", "" }; //N = nonatomic

    objc_property_attribute_t backingivar  = { "V", [[NSString stringWithFormat:@"_%@", propertyName] UTF8String] };  //variable name

    objc_property_attribute_t attrs[] = { type, ownership0, ownership, backingivar };

    class_addProperty(targetClass, [propertyName UTF8String], attrs, 4);

}

动态增加成员变量

  class_addIvar([self.person class], "country", sizeof(NSString *), 0, "@");  //这个方法没有增加上 不知道为什么望知道的亲们说一下

//动态交换二个方法的实现

  Method methodOne = class_getInstanceMethod([self.person class], @selector(sayName));

    Method methodTwo = class_getInstanceMethod([self.person class], @selector(saySex));

    method_exchangeImplementations(methodOne, methodTwo);

    //拦截并替换方法  Person里面的sayName方法被Tool类里面的changeMethod替换了

    Method m1 = class_getInstanceMethod([Person class], @selector(sayName));

    Method m2 = class_getInstanceMethod([Tool class], @selector(changeMethod));

    method_exchangeImplementations(m1, m2);