NSUserDefault中的NSMutableArray，检索NULL

Question

In my class first controller i have:

UITextField * title = textfields [0];
NSString *html = [self.webView stringByEvaluatingJavaScriptFromString:
                  @"document.body.innerHTML"];

InfoHtml * newFeed = [[InfoHtml alloc] init];
NewFeed.title = title.text;
NewFeed.html = html;
                           
[self.arrayHTML addObject: newFeed];
                
NSUserDefaults * userDefaults = [NSUserDefaults standardUserDefaults];[UserDefaults setObject: self.arrayHTML forKey: @ "test"];
[UserDefaults synchronize];

where arrayHTML is a NSMutableArray and InfoHtml is a class model:

@interface InfoHtml : NSObject <NSCoding>
@property (nonatomic,strong) NSString *title;
@property (nonatomic,strong) NSString *html;
@end

In my other controlller, i try to retrieve this array with:

NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];
self.arrayHTML = [userDefaults objectForKey:@"test"];
NSLog(@"%@", self.arrayHTML);

NSLog prints: (null)

Why?

Answer 1

Did you alloc self.arrayHTML anywhere? Can't see it on your code, so maybe you need to alloc it before adding objects.

self.arrayHTML = [[NSMutableArray alloc]init];

or

self.arrayHTML = [NSMutableArray new];

After all it was a lifecycle problem overlapping self.arrayHTML

Answer 2

首先，确保U已经在InfoHtml类中执行了NSCoding委托，并实现- (id)initWithCoder:(NSCoder *)decoder - (void)encodeWithCoder:(NSCoder *)encoder方法