Ios 如何将NSDictionary转换为自定义对象
我有一个json对象:Ios 如何将NSDictionary转换为自定义对象,ios,objective-c,json,nsdictionary,nsjsonserialization,Ios,Objective C,Json,Nsdictionary,Nsjsonserialization,我有一个json对象: @interface Order : NSObject @property (nonatomic, retain) NSString *OrderId; @property (nonatomic, retain) NSString *Title; @property (nonatomic, retain) NSString *Weight; - (NSMutableDictionary *)toNSDictionary; ... - (NSMutableDictio
@interface Order : NSObject
@property (nonatomic, retain) NSString *OrderId;
@property (nonatomic, retain) NSString *Title;
@property (nonatomic, retain) NSString *Weight;
- (NSMutableDictionary *)toNSDictionary;
...
- (NSMutableDictionary *)toNSDictionary
{
NSMutableDictionary *dictionary = [[NSMutableDictionary alloc] init];
[dictionary setValue:self.OrderId forKey:@"OrderId"];
[dictionary setValue:self.Title forKey:@"Title"];
[dictionary setValue:self.Weight forKey:@"Weight"];
return dictionary;
}
在字符串中,这是:
{
"Title" : "test",
"Weight" : "32",
"OrderId" : "55"
}
我使用以下代码获取字符串JSON:
NSMutableDictionary* str = [o toNSDictionary];
NSError *writeError = nil;
NSData *jsonData = [NSJSONSerialization dataWithJSONObject:str options:NSJSONWritingPrettyPrinted error:&writeError];
NSString *jsonString = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];
现在,我需要从JSON字符串创建并映射对象:
NSData *jsonData = [jsonString dataUsingEncoding:NSUTF8StringEncoding];
NSError *e;
NSDictionary *dict = [NSJSONSerialization JSONObjectWithData:jsonData options:nil error:&e];
这是我的字典。
如何从该字典中获取对象?将新的
initWithDictionary:
方法添加到顺序中
:
- (instancetype)initWithDictionary:(NSDictionary*)dictionary {
if (self = [super init]) {
self.OrderId = dictionary[@"OrderId"];
self.Title = dictionary[@"Title"];
self.Weight = dictionary[@"Weight"];
}
return self;
}
不要忘记将initWithDictionary
的签名添加到Order.h
文件中
在获取JSON的方法中:
NSData *jsonData = [jsonString dataUsingEncoding:NSUTF8StringEncoding];
NSError *e;
NSDictionary *dict = [NSJSONSerialization JSONObjectWithData:jsonData options:nil error:&e];
Order *order = [[Order alloc] initWithDictionary:dict];
如果对象上的属性名称与JSON字符串中的键匹配,则可以执行以下操作: 要将JSON字符串映射到对象,首先需要将字符串转换为NSDictionary,然后可以在NSObject上使用使用键值编码来设置每个属性的方法
NSError *error = nil;
NSData *jsonData = ...; // e.g. [myJSONString dataUsingEncoding:NSUTF8Encoding];
NSDictionary *jsonDictionary = [NSJSONSerialization JSONObjectWithData:jsonData options:NSJSONReadingOptionsAllowFragments error:&error];
MyObject *object = [[MyObject alloc] init];
[object setValuesForKeysWithDictionary:jsonDictionary];
如果键不匹配,您可以覆盖对象类中NSObject-[NSObject valueForUndefinedKey:
的实例方法
要将对象映射到JSON,可以使用Objective-C运行时自动进行映射。以下内容适用于任何NSObject子类:
#import <objc/runtime.h>
- (NSDictionary *)dictionaryValue
{
NSMutableArray *propertyKeys = [NSMutableArray array];
Class currentClass = self.class;
while ([currentClass superclass]) { // avoid printing NSObject's attributes
unsigned int outCount, i;
objc_property_t *properties = class_copyPropertyList(currentClass, &outCount);
for (i = 0; i < outCount; i++) {
objc_property_t property = properties[i];
const char *propName = property_getName(property);
if (propName) {
NSString *propertyName = [NSString stringWithUTF8String:propName];
[propertyKeys addObject:propertyName];
}
}
free(properties);
currentClass = [currentClass superclass];
}
return [self dictionaryWithValuesForKeys:propertyKeys];
}
#导入
-(NSDictionary*)字典值
{
NSMutableArray*propertyKeys=[NSMutableArray];
Class currentClass=self.Class;
而([currentClass superclass]){//避免打印NSObject的属性
无符号整数超过,i;
objc_property_t*properties=class_copyPropertyList(currentClass,&outCount);
对于(i=0;i
实现这一点的最佳方法是使用库进行序列化/反序列化
很多图书馆都有,但我喜欢的是
JagPropertyConverter
它可以将自定义对象转换为NSDictionary,反之亦然甚至它还支持转换字典、数组或对象中的任何自定义对象(即合成)
假设属性名称和字典键相同,可以使用此函数转换任何对象
- (void) setObject:(id) object ValuesFromDictionary:(NSDictionary *) dictionary
{
for (NSString *fieldName in dictionary) {
[object setValue:[dictionary objectForKey:fieldName] forKey:fieldName];
}
}
这将更方便您:
- (instancetype)initWithDictionary:(NSDictionary*)dictionary {
if (self = [super init]) {
[self setValuesForKeysWithDictionary:dictionary];}
return self;
}
定义从“AutoBinObject”继承的自定义类。声明与NSDictionary中的键具有相同名称的属性。然后调用方法:
[customObject loadFromDictionary:dic];
实际上,我们可以自定义类来将不同的属性名称映射到字典中的键。除此之外,我们还可以绑定嵌套对象。请看一下这个演示。用法很简单:
如果您有很多对象,则必须逐个实现initWithDictiona。。。还有一些更灵活的解决方案,例如::也可以看到这个问题,但我们可以处理它。是的,很好。如果有任何疑问,请与我联系。如果任何字段丢失,这将崩溃。这将有所帮助。在设置值之前,请检查对象中的字段名。if([object respondsToSelector:NSSelectorFromString(fieldName)]{[object setValue:[dictionary objectForKey:fieldName]forKey:fieldName];}}
[customObject loadFromDictionary:dic];