NSUserDefaults适合存储轻量级本地数据,比如要保存用户登陆的用户名、密码,使用NSUserDefaults是首选。下次再登陆的时候就可以直接从NSUserDefaults里面读取上次登陆的信息。
NSUserDefaults支持的数据格式有:NSNumber(Integer、Float、Double),NSString,NSDate,NSArray,NSDictionary,BOOL类型。
NSUserDefaults,读取方便,容易。下面给出一个示例看看如何使用:
Cpp代码 :
- //保存数据到NSUserDefaults
- -(void)saveNSUserDefaults
- {
- NSString *myString = @\”enuola\”;
- int myInteger = 100;
- float myFloat = 50.0f;
- double myDouble = 20.0;
- NSDate *myDate = [NSDate date];
- NSArray *myArray = [NSArray arrayWithObjects:@\”hello\”, @\”world\”, nil];
- NSDictionary *myDictionary = [NSDictionary dictionaryWithObjects:[NSArray arrayWithObjects:@\”enuo\”, @\”20\”, nil] forKeys:[NSArray arrayWithObjects:@\”name\”, @\”age\”, nil]];
- //将上述数据全部存储到NSUserDefaults中
- NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];
- //存储时,除NSNumber类型使用对应的类型外,其他的都是使用setObject:forKey:
- [userDefaults setInteger:myInteger forKey:@\”myInteger\”];
- [userDefaults setFloat:myFloat forKey:@\”myFloat\”];
- [userDefaults setDouble:myDouble forKey:@\”myDouble\”];
- [userDefaults setObject:myString forKey:@\”myString\”];
- [userDefaults setObject:myDate forKey:@\”myDate\”];
- [userDefaults setObject:myArray forKey:@\”myArray\”];
- [userDefaults setObject:myDictionary forKey:@\”myDictionary\”];
- //这里建议同步存储到磁盘中,但是不是必须的
- [userDefaults synchronize];
- }
- //从NSUserDefaults中读取数据
- -(void)readNSUserDefaults
- {
- NSUserDefaults *userDefaultes = [NSUserDefaults standardUserDefaults];
- //读取数据到各个label中
- //读取整型int类型的数据
- NSInteger myInteger = [userDefaultes integerForKey:@\”myInteger\”];
- txtInteger.text = [NSString stringWithFormat:@\”%d\”,myInteger];
- //读取浮点型float类型的数据
- float myFloat = [userDefaultes floatForKey:@\”myFloat\”];
- txtFloat.text = [NSString stringWithFormat:@\”%f\”,myFloat];
- //读取double类型的数据
- double myDouble = [userDefaultes doubleForKey:@\”myDouble\”];
- txtDouble.text = [NSString stringWithFormat:@\”%f\”,myDouble];
- //读取NSString类型的数据
- NSString *myString = [userDefaultes stringForKey:@\”myString\”];
- txtNSString.text = myString;
- //读取NSDate日期类型的数据
- NSDate *myDate = [userDefaultes valueForKey:@\”myDate\”];
- NSDateFormatter *df = [[NSDateFormatter alloc] init];
- [df setDateFormat:@\”yyyy-MM-dd HH:mm:ss\”];
- txtNSDate.text = [NSString stringWithFormat:@\”%@\”,[df stringFromDate:myDate]];
- //读取数组NSArray类型的数据
- NSArray *myArray = [userDefaultes arrayForKey:@\”myArray\”];
- NSString *myArrayString = [[NSString alloc] init];
- for(NSString *str in myArray)
- {
- NSLog(@\”str= %@\”,str);
- myArrayString = [NSString stringWithFormat:@\”%@ %@\”, myArrayString, str];
- [myArrayString stringByAppendingString:str];
- // [myArrayString stringByAppendingFormat:@\”%@\”,str];
- NSLog(@\”myArrayString=%@\”,myArrayString);
- }
- txtNSArray.text = myArrayString;
- //读取字典类型NSDictionary类型的数据
- NSDictionary *myDictionary = [userDefaultes dictionaryForKey:@\”myDictionary\”];
- NSString *myDicString = [NSString stringWithFormat:@\”name:%@, age:%d\”,[myDictionary valueForKey:@\”name\”], [[myDictionary valueForKey:@\”age\”] integerValue]];
- txtNSDictionary.text = myDicString;
- }
用NSUserDefaults存储的数据下次程序运行的时候依然存在,其数据存储在应用程序内置的一个plist文件里,这个可以根据路径看到。比如说这个是你的程序沙盒位置
/UsersLibrary/Application Support/iPhoneSimulator/4.1/Applicati*****/29788E40-AF47-45A0-8E92-3AC0F501B7F4/,(这个是应用程序对应在mac上的位置)
这个下面有/Library/Prefereces,里面有个plist文件,存储的就是你的userDefaults,想要删掉的话,用removeObjectForKey或者删掉沙盒,也就是你的应用程序然后重新安装。
来自 “ ITPUB博客 ” ,链接:http://blog.itpub.net/12231606/viewspace-1075941/,如需转载,请注明出处,否则将追究法律责任。
转载于:http://blog.itpub.net/12231606/viewspace-1075941/
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