1. 動(dòng)態(tài)變量控制

1）Sense：

Teacher: What's your name?

XiaoMing: My name is XiaoMing.

Teacher: Pardon?

XiaoMing: My name is __

在程序當(dāng)中，假設(shè)XiaoMing的name原來的值為XiaoMing，后來被Runtime偷換了一個(gè)名字叫Minggo。那么，Runtime是如何做到的呢？

2）Step：

①動(dòng)態(tài)獲取XiaoMing類中的所有屬性[當(dāng)然包括私有]

Ivar *ivar = class_copyIvarList([self.xiaoMing class], &count);

②遍歷屬性找到對應(yīng)name字段

const char *varName = ivar_getName(var);

③修改對應(yīng)的字段值成Minggo

object_setIvar(self.xiaoMing, var, @"Minggo");

3）Show Code：

-(void)answer{

???? unsigned int count = 0;

???? Ivar *ivar = class_copyIvarList([self.xiaoMing class], &count);

???? for (int i = 0; i<count; i++){

?????????? Ivar var = ivar[i];

?????????? const char *varName = ivar_getName(var);

?????????? NSString *name = [NSString stringWithUTF8String:varName];

?????????? if ([name isEqualToString:@"_englishName"]) {

?????????????????????? object_setIvar(self.xiaoMing, var, @"Minggo");

?????????????????????? break;

????????????? }

???? }

???? NSLog(@"XiaoMing first answer is %@",self.xiaoMing.englishName);

???? self.nameTf.text = self.xiaoMing.englishName;

}