让Model类遵循NSCoding 和 NSCopying 协议
并实现三个方法：
- (void)encodeWithCoder:(NSCoder *)encoder {
/*
[super encodeWithCoder:encoder];
//If you are subclassing a class that also conforms to NSCoding, you need to make sure you call encodeWithCoder: on your superclass,
*/
[encoder encodeObject:foo forKey:kFooKey];
[encoder encodeObject:bar forKey:kBarKey];
[encoder encodeInt:someInt forKey:kSomeIntKey];
[encoder encodeFloat:someFloat forKey:kSomeFloatKey]
}
- (id)initWithCoder:(NSCoder *)decoder
{
if (self = [super init]) {
//if(self = [super initWithCoder:decoder])
foo = [decoder decodeObjectForKey:kFooKey];
bar = [decoder decodeObjectForKey:kBarKey];
someInt = [decoder decodeIntForKey:kSomeIntKey];
someFloat = [decoder decodeFloatForKey:kAgeKey];
}
return self;
}
- (id)copyWithZone:(NSZone *)zone {
MyClass *copy = [[[self class] allocWithZone:zone] init];
copy.foo = [self.foo copyWithZone:zone];
copy.bar = [self.bar copyWithZone:zone];
copy.someInt = self.someInt;
copy.someFloat = self.someFloat;
return copy;
}
在存储四个textField的字符的例子中，Model代码如下
#pragma mark NSCoding
- (void)encodeWithCoder:(NSCoder *)encoder {
[encoder encodeObject:field1 forKey:kField1Key];
[encoder encodeObject:field2 forKey:kField2Key];
[encoder encodeObject:field3 forKey:kField3Key];
[encoder encodeObject:field4 forKey:kField4Key];
}
- (id)initWithCoder:(NSCoder *)decoder {
if (self = [super init]) {
field1 = [decoder decodeObjectForKey:kField1Key];
field2 = [decoder decodeObjectForKey:kField2Key];
field3 = [decoder decodeObjectForKey:kField3Key];
field4 = [decoder decodeObjectForKey:kField4Key];
}
return self;
}
#pragma mark -
#pragma mark NSCopying
- (id)copyWithZone:(NSZone *)zone {
BIDFourLines *copy = [[[self class] allocWithZone: zone] init];
copy.field1 = [self.field1 copyWithZone:zone];
copy.field2 = [self.field2 copyWithZone:zone];
copy.field3 = [self.field3 copyWithZone:zone];
copy.field4 = [self.field4 copyWithZone:zone];
return copy;
}
依然在ViewController中定义两个方法：
- (NSString *)dataFilePath;
- (void)applicationWillResignActive:(NSNotification *)notification;
#define kFilename @"archive"
#define kDataKey @"Data"
- (NSString *)dataFilePath {
NSArray *paths = NSSearchPathForDirectoriesInDomains(
NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
return [documentsDirectory stringByAppendingPathComponent:kFilename];
}
- (void)applicationWillResignActive:(NSNotification *)notification {
BIDFourLines *fourLines = [[BIDFourLines alloc] init];
fourLines.field1 = field1.text;
fourLines.field2 = field2.text;
fourLines.field3 = field3.text;
fourLines.field4 = field4.text;
NSMutableData *data = [[NSMutableData alloc] init];
NSKeyedArchiver *archiver = [[NSKeyedArchiver alloc]
initForWritingWithMutableData:data];
[archiver encodeObject:fourLines forKey:kDataKey];
[archiver finishEncoding];
[data writeToFile:[self dataFilePath] atomically:YES];
}
之后在viewDidLoad中实现：
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
NSString *filePath = [self dataFilePath];
if ([[NSFileManager defaultManager] fileExistsAtPath:filePath]) {
NSData *data = [[NSMutableData alloc]
initWithContentsOfFile:[self dataFilePath]];
NSKeyedUnarchiver *unarchiver = [[NSKeyedUnarchiver alloc]
initForReadingWithData:data];
BIDFourLines *fourLines = [unarchiver decodeObjectForKey:kDataKey];
[unarchiver finishDecoding];
field1.text = fourLines.field1;
field2.text = fourLines.field2;
field3.text = fourLines.field3;
field4.text = fourLines.field4;
}
UIApplication *app = [UIApplication sharedApplication];
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(applicationWillResignActive:)
name:UIApplicationWillResignActiveNotification
object:app];
}
本文转自老Zhan博客园博客，原文链接：http://www.cnblogs.com/mybkn/archive/2012/03/27/2419054.html，如需转载请自行联系原作者
