一、成员变量
1.1 Ivar
Ivar: 实例变量类型,是一个指向objc_ivar结构体的指针
typedef struct objc_ivar *Ivar;
而objc_ivar的定义如下
struct objc_ivar {
char *ivar_name OBJC2_UNAVAILABLE;
char *ivar_type OBJC2_UNAVAILABLE;
int ivar_offset OBJC2_UNAVAILABLE;
#ifdef __LP64__
int space OBJC2_UNAVAILABLE;
#endif
}
1.2 常用方法
// 获取所有成员变量
class_copyIvarList
// 获取所有方法
class_copyMethodList
// 获取所有属性
ivar_getName
// 获取成员变量类型编码
ivar_getTypeEncoding
// 获取指定名称的成员变量
class_getInstanceVariable
// 获取某个对象成员变量的值
object_getIvar
// 设置某个对象成员变量的值
object_setIvar
1.3 class_copyPropertyList与class_copyIvarList区别
- class_copyPropertyList:仅仅返回属性
- class_copyIvarList:不仅返回属性,还返回变量({}修饰的变量)
//XYPerson.h
#import
@interface XYPerson : NSObject
@property (nonatomic, copy) NSString *name;
@property (nonatomic, assign) NSUInteger age;
@end
//XYPerson.m
#import "XYPerson.h"
@interface XYPerson (){
NSInteger sex;
}
@property (nonatomic, copy) NSString *hobby;
@end
@implementation XYPerson
//MainController.m
- (void)viewDidLoad {
XYPerson *person = [XYPerson new];
{
//记录属性的个数
unsigned int count = 0;
//获取属性列表
Ivar *members = class_copyIvarList([person class], &count);
//遍历属性列表
for (NSInteger i = 0; i < count; i++) {
//取到属性
Ivar ivar = members[i];
//获取属性名
const char *memberName = ivar_getName(ivar);
NSString *ivarName = [NSString stringWithFormat:@"%s", memberName];
NSLog(@"属性名:%@", ivarName);
}
free(members);
}
NSLog(@"----------");
{
//记录属性的个数
unsigned int count = 0;
objc_property_t *properties = class_copyPropertyList([person class], &count);
//遍历属性列表
for (NSInteger i = 0; i < count; i++) {
//取到属性
objc_property_t property = properties[i];
//获取属性名
NSString * propertyName = [NSString stringWithCString:property_getName(property) encoding:NSUTF8StringEncoding];
NSLog(@"属性名:%@", propertyName);
}
free(properties);
}
}
打印如下
2018-03-07 11:26:29.693788+0800 tableView[76444:1687311] 属性名:sex
2018-03-07 11:26:29.694058+0800 tableView[76444:1687311] 属性名:_name
2018-03-07 11:26:29.694371+0800 tableView[76444:1687311] 属性名:_age
2018-03-07 11:26:29.694485+0800 tableView[76444:1687311] 属性名:_hobby
2018-03-07 11:26:29.694636+0800 tableView[76444:1687311] ----------
2018-03-07 11:26:29.694766+0800 tableView[76444:1687311] 属性名:hobby
2018-03-07 11:26:29.694913+0800 tableView[76444:1687311] 属性名:name
2018-03-07 11:26:29.695080+0800 tableView[76444:1687311] 属性名:age
可见class_copyIvarList
还获取了一个变量sex
二、获取类的私有属性和私有方法
有一个XYPerson类
//XYPerson.h
#import
@interface XYPerson : NSObject
@property (nonatomic, copy) NSString *name;
@property (nonatomic, assign) NSUInteger age;
- (void)printInfo;
@end
//XYPerson.m
#import "XYPerson.h"
@interface XYPerson (){
NSInteger sex;
}
@property (nonatomic, copy) NSString *hobby;
- (void)_privateMethod;
@end
@implementation XYPerson
- (void)_privateMethod{
NSLog(@"_privateMethod");
}
- (void)printInfo{
NSLog(@"printInfo");
}
2.1 获取类的私有方法
//MainController.m
- (void)viewDidLoad {
[super viewDidLoad];
unsigned int count = 0;
Method *methods = class_copyMethodList([XYPerson class], &count);
for (int i = 0; i < count; i++) { // 3
NSLog(@"%s", sel_getName(method_getName(methods[i]))); // 4
} // 5
free(methods); // 6
}
打印:
2018-03-07 11:01:14.867925+0800 tableView[75802:1660458] _privateMethod
2018-03-07 11:01:14.868151+0800 tableView[75802:1660458] hobby
2018-03-07 11:01:14.868295+0800 tableView[75802:1660458] setHobby:
2018-03-07 11:01:14.868550+0800 tableView[75802:1660458] printInfo
2018-03-07 11:01:14.868742+0800 tableView[75802:1660458] .cxx_destruct
2018-03-07 11:01:14.868884+0800 tableView[75802:1660458] name
2018-03-07 11:01:14.869020+0800 tableView[75802:1660458] setName:
2018-03-07 11:01:14.869117+0800 tableView[75802:1660458] setAge:
2018-03-07 11:01:14.869215+0800 tableView[75802:1660458] age
你会发现有个.cxx_destruct
方法,这玩意儿大有来头
ARC actually creates a -.cxx_destruct method to handle freeing instance variables. This method was originally created for calling C++ destructors automatically when an object was destroyed.
When the compiler saw that an object contained C++ objects, it would generate a method called .cxx_destruct. ARC piggybacks on this method and emits the required cleanup code within it.
可以了解到,.cxx_destruct方法原本是为了C++对象析构的,ARC借用了这个方法插入代码实现了自动内存释放的工作,详细介绍可看sunnyxx大神的
2.2 获取类的私有属性
- 使用KVC的
valueForKey
//MainController.h
- (void)viewDidLoad {
[super viewDidLoad];
XYPerson *person = [XYPerson new];
[person setValue:@"make love" forKey:@"hobby"];
NSString *propertyName = [person valueForKey:@"hobby"];
NSLog(@"属性:%@", propertyName);
}
那么问题来了,KVC是怎么实现的呢,请移步这里
- 使用runtime的class_copyIvarList拿到所有的属性,非常的,简单粗暴!
- (void)viewDidLoad {
[super viewDidLoad];
XYPerson *person = [XYPerson new];
//记录属性的个数
unsigned int count = 0;
//获取属性列表
Ivar *members = class_copyIvarList([person class], &count);
//遍历属性列表
for (NSInteger i = 0; i < count; i++) {
//取到属性
Ivar ivar = members[i];
//获取属性名
const char *memberName = ivar_getName(ivar);
NSString *ivarName = [NSString stringWithFormat:@"%s", memberName];
NSLog(@"属性名:%@", ivarName);
}
free(members);
}
- 使用runtime的class_getInstanceVariable和object_setIvar,直捣黄龙!
Ivar ivar = class_getInstanceVariable([XYPerson class], "_hobby");
XYPerson *person = [XYPerson new];
object_setIvar(person, ivar, @"make love");
NSString * propertyName = object_getIvar(person, ivar);
NSLog(@"属性名:%@", propertyName);
打印如下:
2018-03-07 10:33:19.989501+0800 tableView[75120:1626828] 属性名:make love
- 使用object_getInstanceVariable,不过ARC下不可用,MRC下可以用,
NSString *propertyName;
XYPerson *person = [XYPerson new];
object_getInstanceVariable(person, "_hobby", (void *)&propertyName);
NSLog(@"属性名:%@", propertyName);
而且object_getIvar还快一些,根据苹果的注释
* @note \c object_getIvar is faster than \c object_getInstanceVariable if the Ivar
* for the instance variable is already known.
三、简化initWithCoder的代码
不使用runtime,需要一个一个的写
//AddressModel.m
#import "AddressModel.h"
@implementation AddressModel
- (id)initWithCoder:(NSCoder *)aDecoder {
if (self = [super init]) {
_name = [aDecoder decodeObjectForKey:@"name"];
_selected = [aDecoder decodeBoolForKey:@"selected"];
_lat = [aDecoder decodeDoubleForKey:@"lat"];
_lng = [aDecoder decodeDoubleForKey:@"lng"];
}
return self;
}
- (void)encodeWithCoder:(NSCoder *)aCoder {
[aCoder encodeObject:_name forKey:@"name"];
[aCoder encodeBool:_selected forKey:@"selected"];
[aCoder encodeDouble:_lat forKey:@"lat"];
[aCoder encodeDouble:_lng forKey:@"lng"];
}
使用了runtime,爽歪歪
#import "AddressModel.h"
#import
@implementation AddressModel
- (id)initWithCoder:(NSCoder *)aDecoder {
if (self = [super init]) {
unsigned int count = 0;
Ivar *members = class_copyIvarList([self class], &count);
for (NSInteger i = 0; i < count; i++) {
Ivar ivar = members[i];
const char *memberName = ivar_getName(ivar);
NSString *key = [[NSString alloc] initWithUTF8String:memberName];
[self setValue:[aDecoder decodeObjectForKey:key] forKey:key];
}
free(members);
}
return self;
}
- (void)encodeWithCoder:(NSCoder *)aCoder {
unsigned int count = 0;
Ivar *members = class_copyIvarList([self class], &count);
for (NSInteger i = 0; i < count; i++) {
Ivar ivar = members[i];
const char *memberName = ivar_getName(ivar);
NSString *key = [[NSString alloc] initWithUTF8String:memberName];
id value = [self valueForKey:key];
[aCoder encodeObject:[self valueForKey:key] forKey:key];
}
}
这里使用initWithCoder是为了遵循NSCoding协议,以便进行持久化存储,持久化存储有NSKeyedArchiver与NSUserDefaults两种方案
- NSKeyedArchiver
//
- (void)viewDidLoad {
[super viewDidLoad];
AddressModel *address = [AddressModel new];
address.name = @"世贸中心";
address.selected = NO;
address.lat = 13.89773;
address.lng = 31.87878;
[NSKeyedArchiver archiveRootObject:address toFile:[[self class] savePath]];
NSData *storedData = [NSKeyedUnarchiver unarchiveObjectWithFile:[[self class] savePath]];
}
+ (NSString *)savePath{
NSString *docPath=[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)lastObject];
NSString *path=[docPath stringByAppendingPathComponent:@"userAddresses"];
return path;
}
- NSUserDefaults
- (void)viewDidLoad {
NSData *theData = [NSKeyedArchiver archivedDataWithRootObject:address];
[[NSUserDefaults standardUserDefaults] setObject:theData forKey:@"addressModel"];
[[NSUserDefaults standardUserDefaults] synchronize];
NSData *bufferData = [[NSUserDefaults standardUserDefaults] objectForKey:@"addressModel"];
NSData *storedData = [NSKeyedUnarchiver unarchiveObjectWithData:bufferData];
}
参考
http://blog.sunnyxx.com/2014/04/02/objc_dig_arc_dealloc/
https://www.jianshu.com/p/d361f169423b