iOS中自动实现对象序列化的方法详解

前言

在iOS 中实现对象序列化，需要遵行NSCoding协议，然后对对象的每个属性进行归档和接档赋值，响应的操作比较繁琐。本文主要介绍利用 runtime遍历属性大大简化代码量，下面来看看详细的介绍吧。

具体实现代码如下:

1.先建立NSobject的分类, 定义可能用到的相关类型

static NSString *intType  = @"i"; // int_32t(枚举int型)
static NSString *longTpye = @"l"; //long类型
static NSString *longlongType= @"q"; // longlong类型
static NSString *BoolType = @"B"; //bool类型
static NSString *floatType = @"f"; // float
static NSString *doubleType = @"d"; // double
static NSString *boolType = @"c";
static NSString *stringType = @"NSString"; // NSString 类型
static NSString *numberType = @"NSNumber"; // NSNumber 类型
static NSString *arrayType = @"arrayType";//array类型
static NSString *imageType = @"UIImage"; // UIImage 类型

然后在归档方法中便利自身的属性名称，并且取出自身属性对应的值，进行存储到本地。此时遍历类属性本身，用到了Ivar指针（定义对象的实例变量，包括类型和名字），具体代码如下

//归档
- (void)encodeWithCoder:(NSCoder *)aCoder
{
 unsigned int count; // 属性个数
 Ivar *varArray = class_copyIvarList([self class], &count);

 for (int i = 0; i < count; i++)
 {
  Ivar var = varArray[i];
  const char *cName = ivar_getName(var); // 属性名c字符串
  NSString *proName = [[NSString stringWithUTF8String:cName] substringFromIndex:1]; //OC字符串,并且去掉下划线 _
  const char *cType = ivar_getTypeEncoding(var); // 获取变量类型，c字符串

  id value = [self valueForKey:proName];
  NSString *proType = [NSString stringWithUTF8String:cType]; // oc 字符串

  if ([proType containsString:@"NSString"]) {
   proType = stringType;
  }
  if ([proType containsString:@"NSNumber"]) {
   proType = numberType;
  }
  if ([proType containsString:@"NSArray"]) {
   proType = arrayType;
  }
  if ([proType containsString:@"UIImage"]) {
   proType = imageType;
  }

  // (5). 根据类型进行编码
  if ([proType isEqualToString:intType] || [proType isEqualToString:boolType] || [proType isEqualToString:BoolType]) {
   [aCoder encodeInt32:[value intValue] forKey:proName];
  }
  else if ([proType isEqualToString:longTpye]) {
   [aCoder encodeInt64:[value longValue] forKey:proName];
  }
  else if ([proType isEqualToString:floatType]) {
   [aCoder encodeFloat:[value floatValue] forKey:proName];
  }
  else if ([proType isEqualToString:longlongType] || [proType isEqualToString:doubleType]) {
   [aCoder encodeDouble:[value doubleValue] forKey:proName];
  }
  else if ([proType isEqualToString:stringType]) { // string 类型
   [aCoder encodeObject:value forKey:proName];
  }
  else if ([proType isEqualToString:numberType]) {
   [aCoder encodeObject:value forKey:proName];
  }
  else if ([proType isEqualToString:arrayType]) {
   [aCoder encodeObject:value forKey:proName];
  }
  else if ([proType isEqualToString:imageType]) { // image 类型
   [aCoder encodeDataObject:UIImagePNGRepresentation(value)];
  }
 }
 free(varArray);
}

其次进行解档，原理和归档差不多，直接上代码

- (instancetype)initWithCoder:(NSCoder *)aDecoder
{
 self = [self init];
 if (self) {

  unsigned int count;
  Ivar *varArray = class_copyIvarList([self class], &count);

  for (int i = 0; i < count; i++) {
   Ivar var = varArray[i];
   const char *cName = ivar_getName(var); // 属性名c字符串
   NSString *proName = [[NSString stringWithUTF8String:cName] substringFromIndex:1]; //OC字符串,并且去掉下划线 _
   const char *cType = ivar_getTypeEncoding(var); // 获取变量类型，c字符串
   NSString *proType = [NSString stringWithUTF8String:cType]; // oc 字符串

   if ([proType containsString:@"NSString"]) {
    proType = stringType;
   }
   if ([proType containsString:@"NSNumber"]) {
    proType = numberType;
   }
   if ([proType containsString:@"NSArray"]) {
    proType = arrayType;
   }
   if ([proType containsString:@"UIImage"]) {
    proType = imageType;
   }

   if ([proType isEqualToString:intType] || [proType isEqualToString:boolType] || [proType isEqualToString:BoolType]) {
    int32_t number = [aDecoder decodeInt32ForKey:proName];
    [self setValue:@(number) forKey:proName];
   }
   else if ([proType isEqualToString:longTpye]) {
    int64_t number = [aDecoder decodeInt64ForKey:proName];
    [self setValue:@(number) forKey:proName];
   }
   else if ([proType isEqualToString:floatType]) {
    float number = [aDecoder decodeFloatForKey:proName];
    [self setValue:@(number) forKey:proName];
   }
   else if ([proType isEqualToString:longlongType] || [proType isEqualToString:doubleType]) {
    double number = [aDecoder decodeFloatForKey:proName];
    [self setValue:@(number) forKey:proName];
   }
   else if ([proType isEqualToString:stringType]) { // string 类型
    NSString *string = [aDecoder decodeObjectForKey:proName];
    [self setValue:string forKey:proName];
   }
   else if ([proType isEqualToString:numberType]) {
    NSString *number = [aDecoder decodeObjectForKey:proName];
    [self setValue:number forKey:proName];
   }
   else if ([proType isEqualToString:arrayType]) {
    NSArray *array = [aDecoder decodeObjectForKey:proName];
    [self setValue:array forKey:proName];
   }
   else if ([proType isEqualToString:imageType]) { // image 类型
    UIImage *image = [UIImage imageWithData:[aDecoder decodeDataObject]];
    [self setValue:image forKey:proName];
   }
  }
 }
 return self;
}

最后也就是存储方法、清除存储的本地缓存和获取本地存储数据的方法

//存储路径
- (NSString *)filePathWithUniqueFlagString:(NSString *)uniqueFlag
{
 NSString *docPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
 NSString *detailPath = [NSString stringWithFormat:@"%@_%@",uniqueFlag,[NSString stringWithUTF8String:object_getClassName(self)]];
 NSString *path = [docPath stringByAppendingPathComponent:detailPath];
 return path;
}


//保存对象数据到本地
- (void)saveDataToLocalWithUniqueFlagKey:(NSString *)uniqueFlagKey
{
 [NSKeyedArchiver archiveRootObject:self toFile:[self filePathWithUniqueFlagString:uniqueFlagKey]];
}


//清空本地存储的对象数据
- (id)getDataFromLocalWithUniqueFlagKey:(NSString *)uniqueFlagKey
{
 return [NSKeyedUnarchiver unarchiveObjectWithFile:[self filePathWithUniqueFlagString:uniqueFlagKey]];
}


//从本地获取对象数据
- (BOOL)removeDataFromLocalWithUniqueFlagKey:(NSString *)uniqueFlagKey
{
 NSError *error = nil;
 [[NSFileManager defaultManager] removeItemAtPath:[self filePathWithUniqueFlagString:uniqueFlagKey] error:&error];
 if (!error) {
  return YES;
 }
 else {
  return NO;
 }
}

完整项目下载地址如下：https://github.com/maxzhang123/MXCoding.git 或者可以本地下载地址：http://xiazai.jb51.net/201705/yuanma/MXCoding(jb51.net).rar

总结

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