从JSONModel看Objective-C的反射机制

NSDictionary* json = (fetch from Internet) ...User* user=[[User alloc] init];user.userId =[json objectForKey:@"userId"];user.nick= [json objectForKey:@"nick"];user.image = [json objectForKey:@"image"];user.age = [json objectForKey:@"age"];...

NSError* err = nil;User* user = [[User alloc] initWithDictionary:json error:&err];

···//inspects the class, get‘s a list of the class properties-(void)__inspectProperties{    //JMLog(@"Inspect class: %@", [self class]);        NSMutableDictionary* propertyIndex = [NSMutableDictionary dictionary];        //temp variables for the loops    Class class = [self class];    NSScanner* scanner = nil;    NSString* propertyType = nil;        // inspect inherited properties up to the JSONModel class    while (class != [JSONModel class]) {        //JMLog(@"inspecting: %@", NSStringFromClass(class));                unsigned int propertyCount;        objc_property_t *properties = class_copyPropertyList(class, &propertyCount);                //loop over the class properties        for (unsigned int i = 0; i < propertyCount; i++) {            JSONModelClassProperty* p = [[JSONModelClassProperty alloc] init];            //get property name            objc_property_t property = properties[i];            const char *propertyName = property_getName(property);            p.name = [NSString stringWithUTF8String:propertyName];                        //JMLog(@"property: %@", p.name);                        //get property attributes            const char *attrs = property_getAttributes(property);            NSString* propertyAttributes = [NSString stringWithUTF8String:attrs];                        if ([propertyAttributes hasPrefix:@"Tc,"]) {                //mask BOOLs as structs so they can have custom convertors                p.structName = @"BOOL";            }                        scanner = [NSScanner scannerWithString: propertyAttributes];                        //JMLog(@"attr: %@", [NSString stringWithCString:attrs encoding:NSUTF8StringEncoding]);            [scanner scanUpToString:@"T" intoString: nil];            [scanner scanString:@"T" intoString:nil];···//finally store the property index in the static property indexobjc_setAssociatedObject(self.class,                         &kClassPropertiesKey,                         [propertyIndex copy],                         OBJC_ASSOCIATION_RETAIN // This is atomic                         );

//returns a list of the model‘s properties-(NSArray*)__properties__{    //fetch the associated object    NSDictionary* classProperties = objc_getAssociatedObject(self.class, &kClassPropertiesKey);    if (classProperties) return [classProperties allValues];    //if here, the class needs to inspect itself    [self __setup__];        //return the property list    classProperties = objc_getAssociatedObject(self.class, &kClassPropertiesKey);    return [classProperties allValues];}