[User Defaults] Attempt to set a non-property-list object () as an NSUserDefaults/CFPreferences valu

开发时使用userDefaults存储数据运行时崩溃，崩溃日志如下所示：

[User Defaults] Attempt to set a non-property-list object (
        (
        "<AllAppsModel: 0x17403cce0>",
        "<AllAppsModel: 0x17403d480>",
                      .
                      .
                      .
    ),
        (
        "<AllAppsModel: 0x17403cce0>",
        "<AllAppsModel: 0x17403d480>",
                      .
                      .
                      .
    )
) as an NSUserDefaults/CFPreferences value for key editColumn

查阅资料发现NSUserDefaults本身不支持自定义对象的存储，但它支持NSData类型，所以在这里尝试把对象装换成NSData类型存储。如下所示：

1.存储时直接把最外层数组转成NSData类型：

NSData *data = [NSKeyedArchiver archivedDataWithRootObject:arr];

2.获取时把data转成数组类型：
NSMutableArray *userDefaultsArr = [NSKeyedUnarchiver unarchiveObjectWithData:data];

直接这样修改运行时崩溃，错误日志如下所示：

*** -[NSKeyedUnarchiver initForReadingWithData:]: data is NULL

发现将AllAppsModel类型变成NSData类型就必须实现归档，在AllAppsModel.h文件中遵守NSCoding协议，在AllAppsModel.m文件中实现encodeWithCoder和initWithCoder 方法。如下所示：

@interface AllAppsModel : NSObject<NSCoding>

//标题
@property (nonatomic, copy)NSString *title;
//图片
@property (nonatomic, copy)NSString *picture;

@end

#import "AllAppsModel.h"

@implementation AllAppsModel

- (void)encodeWithCoder:(NSCoder *)aCoder {
    [aCoder encodeObject:self.title forKey:@"title"];
    [aCoder encodeObject:self.picture forKey:@"picture"];
}

- (id)initWithCoder:(NSCoder *)aDecoder {
    if (self = [super init]) {
        self.title = [aDecoder decodeObjectForKey:@"title"];
        self.picture = [aDecoder decodeObjectForKey:@"picture"];
    }
    return self;
}

@end

这样处理后所有问题就都解决了。