runtime基础知识

/*

     获得类方法：

     Method class_getClassMethod(Class cls , SEL name)

     获得某个类的实例对象方法

     Method class_getInstanceMethod(Class cls , SEL name)

     交换两个方法的实现

     void method_exchangeImplementations(Method m1 , Method m2)

     */

//类方法
Method class1 = class_getClassMethod([Person class], @selector(run));
Method class2 = class_getClassMethod([Person class], @selector(study));
method_exchangeImplementations(class1, class2);
[Person run]; //调用study方法实现
[Person study];//调用run方法实现

//对象方法
Method instance1 = class_getInstanceMethod([Person class], @selector(run));
Method instance2 = class_getInstanceMethod([Person class], @selector(stydy));
method_exchangeImplementations(instance1, instance2);  
Person *person = [[Person alloc]init];
[person run];//调用study实现
[person stydy];//调用run实现
    

//创建UIImage的分类
//.h文件
#import <UIKit/UIKit.h>
@interface UIImage (Category)

+ (UIImage *)CZC_imageNamed:(NSString *)name;
@end

//.m文件
#import "UIImage+Category.h"
#import <objc/runtime.h>
@implementation UIImage (Category)
+ (void)load {
    // 获取两个类的类方法
    Method m1 = class_getClassMethod([UIImage class], @selector(imageNamed:));
    Method m2 = class_getClassMethod([UIImage class], @selector(CZC_imageNamed:));
    // 开始交换方法实现
    method_exchangeImplementations(m1, m2);
}

+ (UIImage *)CZC_imageNamed:(NSString *)name{
    
    double version = [[UIDevice currentDevice].systemVersion doubleValue];
    
    if (version >= 7.0) {

        // 如果系统版本是7.0以上，使用另外一套文件名结尾是‘_os7’的扁平化图片
        name = [name stringByAppendingString:@"_7"];
    }
    return [UIImage CZC_imageNamed:name];
}



UIImageView *imageVIew = [[UIImageView alloc]initWithFrame:CGRectMake(100, 100, 100, 100)];
//最终调用的图片是ios_7
imageVIew.image = [UIImage imageNamed:@"ios"]; 
 [self.view addSubview:imageVIew];

/* set方法，将值value 跟对象object 关联起来（将值value 存储到对象object 中）

 参数 object：给哪个对象设置属性

 参数 key：一个属性对应一个Key，将来可以通过key取出这个存储的值，key 可以是任何类型：double、int 等，建议用char 可以节省字节

 参数 value：给属性设置的值

 参数policy：存储策略 （assign 、copy 、 retain就是strong）

 设置值：

 void objc_setAssociatedObject(id object , const void *key ,id value ,objc_AssociationPolicy policy)

 获得值：

 id objc_getAssociatedObject(id object , const void *key)

 */

//Person分类
//.h文件
#import "Person.h"
@interface Person (Category)<NSCoding>

@property (nonatomic, copy)NSString *name;

@end

//.m文件
#import "Person+Category.h"
#import <objc/runtime.h>

char nameKey;
@implementation Person (Category)
- (void)setName:(NSString *)name{
    objc_setAssociatedObject(self, &nameKey, name, OBJC_ASSOCIATION_COPY);
}
- (NSString *)name{
    
    return objc_getAssociatedObject(self, &nameKey);
}
@end

//创建Person类
#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>
@interface Person : NSObject<NSCoding>
{
    NSString *_userName;
    NSUInteger _userAge;
    int  _uerHeight;
    CGFloat _userMoney;
    CGFloat _userWeight;
    
}
@property (nonatomic, copy)NSString *name;

@property (nonatomic, copy)NSString *age;


//创建Person的分类
//.h文件
#import "Person.h"

@interface Person (Category)<NSCoding>

- (void)getAllIvar;

@end

//.m文件
#import "Person+Category.h"
#import <objc/runtime.h>

@implementation Person (Category)
- (void)getAllIvar{
    
    unsigned int outCount = 0;
    Ivar *ivars = class_copyIvarList([Person class], &outCount);
    
    // 遍历所有成员变量
    for (int i = 0; i < outCount; i++) {
        // 取出i位置对应的成员变量
        Ivar ivar = ivars[i];
        const char *name = ivar_getName(ivar);
        const char *type = ivar_getTypeEncoding(ivar);
        NSLog(@"成员变量名：%s 成员变量类型：%s",name,type);
    }
    // 注意释放内存！
    free(ivars);
    
}

//在controller中调用
 [person getAllIvar];

//创建Teacher类，其中包括Dog对象
//.h文件
#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>
#import "Dog.h"
@interface Teacher : NSObject

@property (nonatomic, copy)NSString *name;

@property (nonatomic, copy)NSString *secondName;

@property (nonatomic, assign)NSUInteger age;

@property (nonatomic, assign)NSUInteger height;

@property (nonatomic, assign)CGFloat money;

@property (nonatomic, strong)Dog *dog;

//当字典的key和模型的属性匹配不上
- (void)setDict:(NSDictionary *)dict;

- (void)sendMessage:(NSString *)word;

@end

//.m文件 Teacher
#import "Teacher.h"
#import <objc/runtime.h>
@implementation Teacher
- (void)setDict:(NSDictionary *)dict {
    
    Class c = self.class;
    while (c &&c != [NSObject class]) {
        
        unsigned int outCount = 0;
        Ivar *ivars = class_copyIvarList(c, &outCount);
        for (int i = 0; i < outCount; i++) {
            Ivar ivar = ivars[i];
            NSString *key = [NSString stringWithUTF8String:ivar_getName(ivar)];
            
            // 成员变量名转为属性名（去掉下划线 _ ）
            key = [key substringFromIndex:1];
            // 取出字典的值
            id value = dict[key];
            
            // 如果模型属性数量大于字典键值对数理，模型属性会被赋值为nil而报错
            if (value == nil) continue;
            
            // 将字典中的值设置到模型上
            [self setValue:value forKeyPath:key];
        }
        free(ivars);
        c = [c superclass];
    }
}
@end

//创建Dog类
//.h文件
#import <Foundation/Foundation.h>
@interface Dog : NSObject

@property (nonatomic, copy)NSString *name;
@property (nonatomic, copy)NSString *color;
@property (nonatomic, assign)NSUInteger age;
@end

//在controller中调用
 NSDictionary *dict = @{
                           @"name":@"夏明",
                           @"age":@33,
                           @"money":@1000
                           };
    //字典赋值模型
    Teacher *teacher = [[Teacher alloc]init];
    [teacher setDict:dict];
    NSLog(@"------teacher---%@", teacher);
    
//两层模型
    NSDictionary *dict2 = @{
                            
                            @"name" : @"小明",
                            @"age" : @40,
                            @"dog" : @{
                                
                                    @"name":@"黑子",
                                    @"color":@"黄"
                                }
                            
                            };
    
    Teacher *teacher2 = [[Teacher alloc]init];
    [teacher2 setObjDict:dict2];
    NSLog(@"----teacher2-----%@", teacher2);

//创建Person类
//.h文件
#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>
@interface Person : NSObject<NSCoding>
@end

//.m文件Person
#import "Person.h"
#import "NSObject+Category.h"
#import <objc/runtime.h>
@implementation Person
// void(*)()
// 默认方法都有两个隐式参数，
void eat(id self,SEL sel)
{
    NSLog(@"%@ %@",self,NSStringFromSelector(sel));
}
// 当一个对象调用未实现的方法，会调用这个方法处理,并且会把对应的方法列表传过来.
// 刚好可以用来判断，未实现的方法是不是我们想要动态添加的方法
+ (BOOL)resolveInstanceMethod:(SEL)sel
{
    if (sel == @selector(eat)) {
        // 动态添加eat方法
        // 第一个参数：给哪个类添加方法
        // 第二个参数：添加方法的方法编号
        // 第三个参数：添加方法的函数实现（函数地址）
        // 第四个参数：函数的类型，(返回值+参数类型) v:void @:对象->self :表示SEL->_cmd
        class_addMethod(self, sel, eat, "v@:");//参数:eat可用(IMP)eat替换
    }
    return [super resolveInstanceMethod:sel];
}
@end
//在controller中调用
//动态添加一个方法，p中没有这个方法
Person *p = [[Person alloc]init];
 [p performSelector:@selector(eat)];


//第二种方式
+ (BOOL)resolveInstanceMethod:(SEL)sel
{
    if (sel == @selector(sendMessage:)) {
        class_addMethod([self class], sel, imp_implementationWithBlock(^(id self, NSString *word) {
            NSLog(@"method resolution way : send message = %@", word);
        }), "v@*");
    }
    
    return YES;
}
//动态添加方法,
 Person *p1 = [[Person alloc]init];
 [p1 sendMessage:@"陈志超"];

//创建Teacher类
//.h
#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>
#import "Dog.h"
@interface Teacher : NSObject

@end
//.m
#import "Teacher.h"
#import <objc/runtime.h>
@implementation Teacher

/* 实现方式一
//消息转发，让另一个类对象执行方法
- (id)forwardingTargetForSelector:(SEL)aSelector
{
    if (aSelector == @selector(sendMessage:)) {
        
        return [[Dog alloc]init];
    }
    return nil;
}
*/
//下面两个方式结合为方式二
#pragma mark - Normal Forwarding
- (NSMethodSignature *)methodSignatureForSelector:(SEL)aSelector
{
    NSMethodSignature *methodSignature = [super methodSignatureForSelector:aSelector];
    
    if (!methodSignature) {
        
        methodSignature = [NSMethodSignature signatureWithObjCTypes:"v@:*"];
    }
    
    return methodSignature;
}

- (void)forwardInvocation:(NSInvocation *)anInvocation
{
    Dog *messageForwarding = [[Dog alloc]init];
    
    if ([messageForwarding respondsToSelector:anInvocation.selector]) {
        
        [anInvocation invokeWithTarget:messageForwarding];
    }
}
@end


//创建Dog类
#import <Foundation/Foundation.h>
@interface Dog : NSObject

- (void)sendMessage:(NSString *)word;

@end

#import "Dog.h"
@implementation Dog
- (void)sendMessage:(NSString *)word{
    
    NSLog(@"Dog--sendMessage = %@", word);
}
@end

//此时在controller中，
Teacher *t = [[Teacher alloc] init];
//下面代码会调用Dog的sendMessage方法
[t sendMessage:@"你好，teacher"];