Foundation Framework 轻量级本地数据存储 NSUserDefaults

NSUserDefaults是一种轻量级本地数据存储，是一个永久的NSDictionary，适合存放少量数据，

操作方便，但仅支持NSNumber（Integer、Float、Double），NSString，NSDate，NSArray，NSDictionary，BOOL类型

//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意外，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;
}

NSUserDefaults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。