iOS runtime (3)

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;

}