NSUserDefaults適合存儲輕量級的本地數據，比如要保存一個登陸界面的數據，用戶名、密碼之類的，個人覺得使用NSUserDefaults是首選。下次再登陸的時候就可以直接從NSUserDefaults里面讀取上次登陸的信息咯。
因為如果使用自己建立的plist文件什么的，還得自己顯示創建文件，讀取文件，很麻煩，而是用NSUserDefaults則不用管這些東西，就像讀字符串一樣，直接讀取就可以了。
NSUserDefaults支持的數據格式有：NSNumber（Integer、Float、Double），NSString，NSDate，NSArray，NSDictionary，BOOL類型。很實用吧
NSUserDefaults很方便，讀取也很容易。下面給出一個示例看看如何使用：（PS：更詳細的也可以參考官方文檔哈）
ViewController.h文件中主要是放幾個控件，用于顯示存儲的數據：
#import@interface ViewController : UIViewController
{
IBOutlet UILabel *txtInteger;
IBOutlet UILabel *txtFloat;
IBOutlet UILabel *txtDouble;
IBOutlet UILabel *txtNSString;
IBOutlet UILabel *txtNSDate;
IBOutlet UILabel *txtNSArray;
IBOutlet UILabel *txtNSDictionary;
}
@end
ViewController.m文件中最重要的是兩個方法：
saveNSUserDefaults：用于將各種類型數據保存到NSUserDefaults中
readNSUserDefautls：用于從NSUserDefaults中讀取各種類型的數據。在viewDidLoad中調用這兩個方法就可以看出結果咯
#import "ViewController.h"
@interface ViewController ()
@end
@implementation ViewController
- (void)viewDidLoad
{
[super viewDidLoad];
[self saveNSUserDefaults];? //調用此方法將各種數據存儲到NSUserDefautls中，在下面定義
[self readNSUserDefaults];? //調用此方法從NSUserDefautls中讀取各種數據，在下面定義
}
- (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];
}
//保存數據到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]];
//將上述數據全部存儲到NSUserDefaults中
NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];
//存儲時，除NSNumber類型使用對應的類型意外，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"];
//這里建議同步存儲到磁盤中，但是不是必須的
[userDefaults synchronize];
}
//從NSUserDefaults中讀取數據
-(void)readNSUserDefaults
{
NSUserDefaults *userDefaultes = [NSUserDefaults standardUserDefaults];
//讀取數據到各個label中
//讀取整型int類型的數據
NSInteger myInteger = [userDefaultes integerForKey:@"myInteger"];
txtInteger.text = [NSString stringWithFormat:@"%d",myInteger];
//讀取浮點型float類型的數據
float myFloat = [userDefaultes floatForKey:@"myFloat"];
txtFloat.text = [NSString stringWithFormat:@"%f",myFloat];
//讀取double類型的數據
double myDouble = [userDefaultes doubleForKey:@"myDouble"];
txtDouble.text = [NSString stringWithFormat:@"%f",myDouble];
//讀取NSString類型的數據
NSString *myString = [userDefaultes stringForKey:@"myString"];
txtNSString.text = myString;
//讀取NSDate日期類型的數據
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]];
//讀取數組NSArray類型的數據
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;
//讀取字典類型NSDictionary類型的數據
NSDictionary *myDictionary = [userDefaultes dictionaryForKey:@"myDictionary"];
NSString *myDicString = [NSString stringWithFormat:@"name:%@, age:%d",[myDictionary valueForKey:@"name"], [[myDictionary valueForKey:@"age"] integerValue]];
txtNSDictionary.text = myDicString;
}
@end
