【发布时间】：2014-05-31 22:24:37
【问题描述】：
我的问题： saveInBackground 不起作用。
它不起作用的原因：我正在使用 NSKeyedArchiving 将存储在 NSArray 中的 PFObjects 保存到文件中。我这样做的方法是通过这个library 实现NSCoding。由于某些我不知道的原因，正在添加其他几个字段并将其设置为 NULL。我感觉这搞砸了对saveInBackground 的API 调用。当我在第一组对象（NSKeyedArchiving 之前）上调用 saveInBackground 时，saveInBackground 工作得很好。但是，当我在第二个对象（NSKeyedArchiving 之后）上调用它时，它不会保存。这是为什么呢？
保存
[NSKeyedArchiver archiveRootObject:_myArray toFile:[self returnFilePathForType:@"myArray"]];
检索
_myArray = (NSMutableArray *)[NSKeyedUnarchiver unarchiveObjectWithFile:
[self returnFilePathForType:@"myArray"]];
NSArchiving 之前的对象
2014-04-16 16:34:56.267 myApp[339:60b]
<UserToMessage:bXHfPM8sDs:(null)> {
from = "<PFUser:sdjfa;lfj>";
messageText = "<MessageText:asdffafs>";
read = 0;
to = "<PFUser:asdfadfd>";
}
2014-04-16 16:34:56.841 myApp[339:60b]
<UserToMessage:bXHsdafdfs:(null)> {
from = "<PFUser:eIasdffoF3gi>";
messageText = "<MessageText:asdffafs>";
read = 1;
to = "<PFUser:63sdafdf5>";
}
NSArchiving 后的对象
<UserToMessage:92GGasdffVQLa:(null)> {
ACL = "<null>";
createdAt = "<null>";
from = "<PFUser:eIQsadffF3gi>";
localId = "<null>";
messageText = "<MessageText:EudsaffdHpc>";
objectId = "<null>";
parseClassName = "<null>";
read = 0;
saveDelegate = "<null>";
to = "<PFUser:63spasdfsxNp5>";
updatedAt = "<null>";
}
2014-04-16 16:37:46.527 myApp[352:60b]
<UserToMessage:92GadfQLa:(null)> {
ACL = "<null>";
createdAt = "<null>";
from = "<PFUser:eIQsadffF3gi>";
localId = "<null>";
messageText = "<MessageText:EuTndasHpc>";
objectId = "<null>";
parseClassName = "<null>";
read = 1;
saveDelegate = "<null>";
to = "<PFUser:63spPsadffp5>";
updatedAt = "<null>";
}
使用 Florent 的 PFObject 类别更新：
PFObject+MyPFObject_NSCoding.h
#import <Parse/Parse.h>
@interface PFObject (MyPFObject_NSCoding)
-(void) encodeWithCoder:(NSCoder *) encoder;
-(id) initWithCoder:(NSCoder *) aDecoder;
@end
@interface PFACL (extensions)
-(void) encodeWithCoder:(NSCoder *) encoder;
-(id) initWithCoder:(NSCoder *) aDecoder;
@end
PFObject+MyPFObject_NSCoding.m
#import "PFObject+MyPFObject_NSCoding.h"
@implementation PFObject (MyPFObject_NSCoding)
#pragma mark - NSCoding compliance
#define kPFObjectAllKeys @"___PFObjectAllKeys"
#define kPFObjectClassName @"___PFObjectClassName"
#define kPFObjectObjectId @"___PFObjectId"
#define kPFACLPermissions @"permissionsById"
-(void) encodeWithCoder:(NSCoder *) encoder{
// Encode first className, objectId and All Keys
[encoder encodeObject:[self className] forKey:kPFObjectClassName];
[encoder encodeObject:[self objectId] forKey:kPFObjectObjectId];
[encoder encodeObject:[self allKeys] forKey:kPFObjectAllKeys];
for (NSString * key in [self allKeys]) {
[encoder encodeObject:self[key] forKey:key];
}
}
-(id) initWithCoder:(NSCoder *) aDecoder{
// Decode the className and objectId
NSString * aClassName = [aDecoder decodeObjectForKey:kPFObjectClassName];
NSString * anObjectId = [aDecoder decodeObjectForKey:kPFObjectObjectId];
// Init the object
self = [PFObject objectWithoutDataWithClassName:aClassName objectId:anObjectId];
if (self) {
NSArray * allKeys = [aDecoder decodeObjectForKey:kPFObjectAllKeys];
for (NSString * key in allKeys) {
id obj = [aDecoder decodeObjectForKey:key];
if (obj) {
self[key] = obj;
}
}
}
return self;
}
@end
【问题讨论】：
-
到目前为止，我还没有使用 NSKeyedArchiving 并且看不到任何意义。只需将您的数组保存到文件中，我猜 saveinbackground 不支持 NSKeyedArchiving 对象。有什么问题请告诉我。
-
@walle84 如何将其保存到文件而不保存到后台？
-
尝试在不使用 NSKeyedArchiving 的情况下保存并创建数组并尝试 saveinbackground。检查此link 可能会对您有所帮助。
-
你知道你可以在保存时保存各种对象吗？ [PFObject saveAllInBackground:];
-
@walle84 你是正确的 NSKeyedArchiver 是问题，但是我现在需要一个替代解决方案来保存到磁盘。
标签： ios objective-c parse-platform nskeyedarchiver nscoding