项目中使用JSONModel解析接口返回时，遇到一个model对应多个接口字段，例如

A:
contacts = (
{
  contactId = xx;
  contactName = "xx";
},
{
  contactId = xx;
  contactName = "xx";
}
);

B:
contacts = (
{
  id = xx;
  name = "xxx";
},
{
  id = xx;
  name = "xx";
}
);

对应的model

@protocol MSContactModel;

@interface MSContactModel : JSONModel

@property (nonatomic, strong) NSString *name;
@property (nonatomic, strong) NSString *contactType;
@property (nonatomic, strong) NSString *cellphone;
@property (nonatomic, strong) NSString *telephone;
@property (nonatomic, strong) NSString *email;
@property (nonatomic, strong) NSString *contactId;

@end

.m

+(JSONKeyMapper *)keyMapper
{
  NSMutableDictionary *keyMapper = [NSMutableDictionary dictionary];
  [keyMapper setObject:@"id" forKey:@"contactId"];
  [keyMapper setObject:@"name" forKey:@"contactName"];
  return [[JSONKeyMapper alloc] initWithDictionary:keyMapper];
}

这样会造成接口返回字段为name时，不能正确解析。
原因是
JSONModel.m

-(BOOL)__importDictionary:(NSDictionary*)dict withKeyMapper:(JSONKeyMapper*)keyMapper validation:(BOOL)validation error:(NSError**)err
{
    //loop over the incoming keys and set self's properties
    for (JSONModelClassProperty* property in [self __properties__]) {
        
        //convert key name ot model keys, if a mapper is provided
        NSString* jsonKeyPath = (keyMapper||globalKeyMapper) ? [self __mapString:property.name withKeyMapper:keyMapper importing:YES] : property.name;//这里会根据keyMapper返回
        //JMLog(@"keyPath: %@", jsonKeyPath);
        
        //general check for data type compliance
        id jsonValue;
        @try {
            jsonValue = [dict valueForKeyPath: jsonKeyPath];
        }
        @catch (NSException *exception) {
            jsonValue = dict[jsonKeyPath];
        }

解决方法
JSONModel.m

-(BOOL)__importDictionary:(NSDictionary*)dict withKeyMapper:(JSONKeyMapper*)keyMapper validation:(BOOL)validation error:(NSError**)err
{
    //loop over the incoming keys and set self's properties
    for (JSONModelClassProperty* property in [self __properties__]) {
        
        //convert key name ot model keys, if a mapper is provided
        NSString*jsonKeyPath = nil;
        //JMLog(@"keyPath: %@", jsonKeyPath);
        
        //这里先判断是否可以直接解析
        if (dict[property.name]) {
            jsonKeyPath = property.name;
        }else{
            jsonKeyPath = (keyMapper) ? [self __mapString:property.name withKeyMapper:keyMapper importing:YES] : property.name;
        }
        //general check for data type compliance
        id jsonValue;
        @try {
            jsonValue = [dict valueForKeyPath: jsonKeyPath];
        }
        @catch (NSException *exception) {
            jsonValue = dict[jsonKeyPath];
        }

由于直接修改源码会导致，更新pod的时候会被覆盖，所以创建Category
JSONModel+Track

JSONModel+Track.m

...........
if (dict[property.name]) {
            jsonKeyPath = property.name;
        }else{
            jsonKeyPath = (keyMapper) ? [self __mapString:property.name withKeyMapper:keyMapper importing:YES] : property.name;
        }
...........

代码 FixJSONModel

参考

Single Model with multiple KeyMappers for serializing
JSONModel命名中的驼峰(CamelCase)与下划线 (UnderscoreCase)