IOS中NSUserDefaults的用法（轻量级本地数据存储）

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];

    [self saveNSUserDefaults];  //调用此方法将各种数据存储到NSUserDefautls中，在下面定义
    [self readNSUserDefaults];  //调用此方法从NSUserDefautls中读取各种数据，在下面定义
}

- (void)viewDidUnload
{
    [txtNSString release];
    txtNSString = nil;
    [txtNSDate release];
    txtNSDate = nil;
    [txtNSArray release];
    txtNSArray = nil;
    [txtNSDictionary release];
    txtNSDictionary = nil;
    [txtInteger release];
    txtInteger = nil;
    [txtFloat release];
    txtFloat = nil;
    [txtDouble release];
    txtDouble = nil;
    [super viewDidUnload];
    // Release any retained subviews of the main view.
}

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    return (interfaceOrientation != UIInterfaceOrientationPortraitUpsideDown);
}

- (void)dealloc {
    [txtNSString release];
    [txtNSDate release];
    [txtNSArray release];
    [txtNSDictionary release];
    [txtInteger release];
    [txtFloat release];
    [txtDouble release];
    [super dealloc];
}

//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;
}

@end