FMDB将对象放进数据库[二](使用runtime)

时间:2025-02-25 21:34:44

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上次写了一篇利用FMDB将对象放进数据库

http://www.cnblogs.com/hanjian/p/4344112.html

像我写的HJShop是及其简单的,如果对象有很多属性,那岂不是很麻烦

这里我们就要用到运行时机制了

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

得到对象所有的属性,然后遍历所有属性进行ecode和dcode

听起来可能有些复杂其实只要稍稍改写一下两个方法就可以了

下面开始正文:导入头文件是必不可少的

#import <objc/runtime.h>

下面是运用运行时写的方法,当然KVC在这里不可少(KVC本身就是运行时的一部分)

- (void)encodeWithCoder:(NSCoder *)aCoder

{

unsigned int count = 0;

Ivar *ivars = class_copyIvarList([self class], &count);

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

Ivar ivar = ivars[i];

const char *name = ivar_getName(ivar);

NSString *key = [NSString stringWithUTF8String:name];

[aCoder encodeObject:[self valueForKeyPath:key] forKey:key];

}

free(ivars);

}

- (id)initWithCoder:(NSCoder *)aDecoder

{

if (self = [super init]) {

unsigned int count = 0;

Ivar *ivars = class_copyIvarList([self class], &count);

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

Ivar ivar = ivars[i];

const char *name = ivar_getName(ivar);

NSString *key = [NSString stringWithUTF8String:name];

[self setValue:[aDecoder decodeObjectForKey:key] forKey:key];

}

free(ivars);

}

return self;

}

总结:运行时很强大,变量、类、方法都可以改写。有时间再详细讲讲。

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

获取某个类内部的所有成员变量

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

获取某个类内部所有方法

Method class_getInstanceMethod(Class cls, SEL name)

获取某个实例方法(对象方法,减号-开头)

Method class_getClassMethod(Class cls, SEL name)

获取某个类方法(加号+开头)

void method_exchangeImplementations(Method m1, Method m2)

交换两个方法