读取 类内参数

unsigned int outCount = 0, i = 0;
objc_property_t *properties = class_copyPropertyList([NSURL class], &outCount);
for (i = 0; i < outCount; i++) {
objc_property_t property = properties[i];
NSString *propertyName = [NSString stringWithCString:property_getName(property) encoding:NSUTF8StringEncoding];
NSLog(@" %@ : %@ \n", propertyName, [url valueForKey:propertyName]);// pathForOriginalImageFile
}
free(properties);