(转发)IOS高级开发～Runtime（三）

11、系统类的方法实现部分替换

- (void) methodExchange {

Method m1 = class_getInstanceMethod([NSStringclass],@selector(lowercaseString));

Method m2 = class_getInstanceMethod([NSStringclass],@selector(uppercaseString));

method_exchangeImplementations(m1, m2);

NSLog(@"%@", [@"sssAAAAss"lowercaseString]);

NSLog(@"%@", [@"sssAAAAss"uppercaseString]);

}

打印结果：（仔细看log）

2013-07-26 16:33:22.776 HighOC[7104:c07] SSSAAAASS

2013-07-26 16:33:22.778 HighOC[7104:c07] sssaaaass

12、自定义类的方法实现部分替换

- (void) justLog1 {

NSLog(@"justLog1");

}

- (void) justLog2 {

NSLog(@"justLog2");

}

- (void) methodSetImplementation {

Method method =
class_getInstanceMethod([ClassMethodViewCtrclass],@selector(justLog1));

IMP originalImp = method_getImplementation(method);

Method m1 = class_getInstanceMethod([ClassMethodViewCtrclass],@selector(justLog2));

method_setImplementation(m1, originalImp);

}

//[self methodSetImplementation];

//[self justLog2];

13、覆盖系统方法

IMP cFuncPointer;

IMP cFuncPointer1;

IMP cFuncPointer2;

NSString* CustomUppercaseString(idself,SEL_cmd){

printf("真正起作用的是本函数CustomUppercaseString\r\n");

NSString *string = cFuncPointer(self,_cmd);

return string;

}

NSArray* CustomComponentsSeparatedByString(idself,SEL_cmd,NSString *str){

printf("真正起作用的是本函数CustomIsEqualToString\r\n");

return cFuncPointer1(self,_cmd, str);

}

//不起作用，求解释

bool CustomIsEqualToString(idself,SEL_cmd,NSString *str) ｛

printf("真正起作用的是本函数CustomIsEqualToString\r\n");

return cFuncPointer2(self,_cmd, str);

}

- (void) replaceMethod{

cFuncPointer = [NSStringinstanceMethodForSelector:@selector(uppercaseString)];

class_replaceMethod([NSStringclass],@selector(uppercaseString), (IMP)CustomUppercaseString,"@@:");

cFuncPointer1 = [NSStringinstanceMethodForSelector:@selector(componentsSeparatedByString:)];

class_replaceMethod([NSStringclass],@selector(componentsSeparatedByString:), (IMP)CustomComponentsSeparatedByString,"@@:@");

cFuncPointer2 = [NSStringinstanceMethodForSelector:@selector(isEqualToString:)];

class_replaceMethod([NSStringclass],@selector(isEqualToString:), (IMP)CustomIsEqualToString,"B@:@");

}

14、自动序列化（转）

#import "NSObject+AutoEncodeDecode.h"

@implementation NSObject (AutoEncodeDecode)

- (void)encodeWithCoder:(NSCoder *)encoder {

Class cls = [selfclass];

while (cls != [NSObjectclass]) {

unsigned int numberOfIvars =0;

Ivar* ivars = class_copyIvarList(cls, &numberOfIvars);

for(const
Ivar* p = ivars; p < ivars+numberOfIvars; p++){

Ivar const ivar = *p;

const char *type =ivar_getTypeEncoding(ivar);

NSString *key = [NSStringstringWithUTF8String:ivar_getName(ivar)];

id value = [selfvalueForKey:key];

if (value) {

switch (type[0]) {

case _C_STRUCT_B: {

NSUInteger ivarSize =0;

NSUInteger ivarAlignment =0;

NSGetSizeAndAlignment(type, &ivarSize, &ivarAlignment);

NSData *data = [NSDatadataWithBytes:(constchar *)self +
ivar_getOffset(ivar)

length:ivarSize];

[encoder encodeObject:dataforKey:key];

}

break;

default:

[encoder encodeObject:value

forKey:key];

break;

}

}

}

free(ivars);

cls = class_getSuperclass(cls);

}

}

- (id)initWithCoder:(NSCoder *)decoder {

self = [self
init];

if (self) {

Class cls = [selfclass];

while (cls != [NSObjectclass]) {

unsigned int numberOfIvars =0;

Ivar* ivars =
class_copyIvarList(cls, &numberOfIvars);

for(constIvar* p = ivars; p < ivars+numberOfIvars; p++){

Ivar const ivar = *p;

const char *type =ivar_getTypeEncoding(ivar);

NSString *key = [NSStringstringWithUTF8String:ivar_getName(ivar)];

id value = [decoder
decodeObjectForKey:key];

if (value) {

switch (type[0]) {

case
_C_STRUCT_B: {

NSUInteger ivarSize =0;

NSUInteger ivarAlignment =0;

NSGetSizeAndAlignment(type, &ivarSize, &ivarAlignment);

NSData *data = [decoderdecodeObjectForKey:key];

char *sourceIvarLocation = (char*)self+ivar_getOffset(ivar);

[data getBytes:sourceIvarLocationlength:ivarSize];

}

break;

default:

[self
setValue:[decoder decodeObjectForKey:key]

forKey:key];

break;

}

}

}

free(ivars);

cls = class_getSuperclass(cls);

}

}

return self;

}

IOS高级开发～Runtime（一）

http://blog.csdn.net/zfpp25_/article/details/9496705

IOS高级开发～Runtime（二）

http://blog.csdn.net/zfpp25_/article/details/9497187

IOS高级开发～Runtime（三）

http://blog.csdn.net/zfpp25_/article/details/9497721

IOS高级开发～Runtime（四）

http://blog.csdn.net/zfpp25_/article/details/9498233