objc_property_attribute_t 的value和name

获取一个属性的attributes

@interface person : NSObject
@property (nonatomic, strong) NSString *name;
@end

int main(){
  unsigned int outCount = 0;
  objc_property_t *properties = class_copyPropertyList([person class], &outCount);
  for(int i = 0; i < outCount; i++){
    unsigned int count = 0;
    objc_property_attribute_t *attributes = property_copyAttributesList(properties[i], &count);
    for(int j = 0; j < count; j++){
   <span style="white-space:pre">	</span>NSLog(@"attribute.name = %s, attribute.value = %s", attributes[j].name, attributes[j].value); 
    }
  }
  return 0;
}

objc_property_attribute_t的value和name

常用attribute	name	value
nonatomic	"N"	""
strong/retain	"&"	""
weak	"W"	""
属性的类型type	"T"	"@TypeName", eg"@\"NSString\""
属性对应的实例变量Ivar	"V"	"Ivar_name", eg "_name"
readonly	"R"	""
getter	"G"	"GetterName", eg"isRight"
setter	"S"	"SetterName", eg"setName"
assign/atomic	默认即为assign和retain

动态添加属性

@interface person : NSObjec{
  NSString *_name;
}
int main(){
  objc_property_attribute_t nonatomic = {"N", ""};
  objc_property_attribute_t strong = {"&", ""};
  objc_property_attribute_t type = {"T", "@\"NSString\""};
  objc_property_attribute_t ivar = {"V", "_name"};
  objc_property_attribute_t attributes[] = {nonatomic, strong, type, ivar};
  BOOL result = class_addProperty([person class], "name", attributes, 4);
}