我写的RunTime函数之一，为类的某个属性赋值以及方法交换

 1，为属性赋值

#import <UIKit/UIKit.h>

@interface UIViewController (RunTime)

- (BOOL)setPropertyValue:(id)propertyValue propertyName:(NSString *)propertyName ;

@end

#import "UIViewController+RunTime.h"

@implementation UIViewController (Change)

/**
 给指定property赋值；若property不存在，则不做

 @param propertyValue property值， propertyName：property的名字
 */
- (BOOL)setPropertyValue:(id)propertyValue propertyName:(NSString *)propertyName {
    
    BOOL isPropertyExist= NO;
    unsigned int methodCount = 0;
    
    Ivar * ivars = class_copyIvarList([self class], &methodCount);
    for (unsigned int i = 0; i < methodCount; i ++) {
        Ivar ivar = ivars[i];
        const char * name = ivar_getName(ivar);
        const char * type = ivar_getTypeEncoding(ivar);
        NSLog(@"%@拥有的成员变量的类型为%s，名字为 %s ",NSStringFromClass([self class]),type, name);
        NSString *tempPropertyName = [[NSString alloc] initWithCString:name encoding:NSUTF8StringEncoding];
        if([tempPropertyName isEqualToString:propertyName])
        {
            isPropertyExist = YES;
            object_setIvar(self, ivar,propertyValue);
            NSLog(@"object_setIvar:%@",object_getIvar(self, ivar));
            break;
        }
    }
    return isPropertyExist;
}

@end

 2，方法交换

#import <UIKit/UIKit.h>

@interface UIViewController (Reachability)


/**
 将检测网络的函数替换，不做任何事情
 使用方法：viewWillAppear中调用该函数，将EcoInitTools类中的reachabilityChanged方法实现替换成doNothing函数实现，
 viewWillDisappear中再替换回来。
 */
- (void)changeReachability;

@end



#import "UIViewController+Reachability.h"

@implementation UIViewController (Reachability)

+ (void)load {
    EcoLog(@"UIViewController (Reachability):%@",NSStringFromClass([self class]));
}


/**
 替换的函数
 */
- (void)doNothing {
    NSLog(@"doNothing");
}

- (void)changeReachability {
    
    Class ecoTools = NSClassFromString(@"EcoInitTools");
    
    // 获取reachabilityChanged方法地址
    Method doSomeThingMethod = class_getInstanceMethod(ecoTools, @selector(reachabilityChanged:));
    Method doNothingMethod = class_getInstanceMethod([self class], @selector(doNothing));
    
    // 交换方法地址，相当于交换实现方式
    method_exchangeImplementations(doSomeThingMethod, doNothingMethod);
}




@end