Object c 反射

Object c也有和java相同的方法获取对象的属性列表方法，也就时反射了。

http://developer.apple.com/library/mac/#documentation/Cocoa/Reference/ObjCRuntimeRef/Reference/reference.html

下面这段代码演示了如何获取类的属性相关信息

#import <objc/runtime.h>

#import <Foundation/Foundation.h>

unsigned int outCount, i;

objc_property_t *properties = class_copyPropertyList([UITouch class], &outCount);

for(i = 0; i < outCount; i++) {

    objc_property_t property = properties[i];

    fprintf(stdout, "%s %s\n", property_getName(property), property_getAttributes(property));

}

free(properties);



参考文档

http://stackoverflow.com/questions/754824/get-an-object-attributes-list-in-objective-c

反射在NSCoding里如何试用

NSCoding里如果要实现其协议的话，要定义很多Key，如果属性比较多的话，就比较繁琐。
但是如果用反射的话，就很容易了。
 

- (void)encodeWithCoder:(NSCoder*)coder
{
    Class clazz = [self class];
    u_int count;
    
    objc_property_t* properties = class_copyPropertyList(clazz, &count);
    NSMutableArray* propertyArray = [NSMutableArray arrayWithCapacity:count];
    for (int i = 0; i < count ; i++)
    {
        const char* propertyName = property_getName(properties[i]);
        [propertyArray addObject:[NSString  stringWithCString:propertyName encoding:NSUTF8StringEncoding]];
    }
    free(properties);
    
    
    for (NSString *name in propertyArray)
    {
        id value = [self valueForKey:name];
        [coder encodeObject:value forKey:name];
    }
}

- (id)initWithCoder:(NSCoder*)decoder
{
    if (self = [super init])
    {
        if (decoder == nil)
        {
            return self;
        }
        
        Class clazz = [self class];
        u_int count;
        
        objc_property_t* properties = class_copyPropertyList(clazz, &count);
        NSMutableArray* propertyArray = [NSMutableArray arrayWithCapacity:count];
        for (int i = 0; i < count ; i++)
        {
            const char* propertyName = property_getName(properties[i]);
            [propertyArray addObject:[NSString  stringWithCString:propertyName encoding:NSUTF8StringEncoding]];
        }
        free(properties);
        
        
        for (NSString *name in propertyArray)
        {
            id value = [decoder decodeObjectForKey:name];   
            [self setValue:value forKey:name];
        }
    }
    return self;
}