IOS高级开发～Runtime（三）

 iOS高级开发～Runtime（一）

 iOS高级开发～Runtime（二）

 iOS高级开发～Runtime（三）

 iOS高级开发～Runtime（四）
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;
}