简单的翻译下，keychain可以存储密码、证书等等，至于有什么好处，呵呵哒，自己百度去吧，总结一点就是更安全，而且取的更方便吧，看app场景吧。
本次代码，分为两段，一段为保存代码
1 - (BOOL)saveData:(NSString *)str
2 {
3 OSStatus status = noErr;
4 NSMutableDictionary *query = [[NSMutableDictionary alloc] init];
5 [query setObject:(id)kSecClassGenericPassword forKey:(id)kSecClass];
6 /// query one
7 [query setObject:(id)kSecMatchLimitOne forKey:(id)kSecMatchLimit];
8 [query setObject:@"password" forKey:(id)kSecAttrService];
9 CFMutableDictionaryRef outDicRef = nil;
10 status = SecItemCopyMatching((CFDictionaryRef)query, (CFTypeRef *)&outDicRef);
11 if(status==noErr)
12 {
13 NSLog(@"#######################query success");
14 [query removeObjectForKey:(id)kSecMatchLimit];
15 NSLog(@"=============code %d",SecItemDelete((CFDictionaryRef)query));
16 NSMutableDictionary *dt = [[NSMutableDictionary alloc] init];
17 [dt setObject:@"label" forKey:(id)kSecAttrLabel];
18 [dt setObject:@"password" forKey:(id)kSecAttrService];
19 [dt setObject:[str dataUsingEncoding:NSUTF8StringEncoding] forKey:(id)kSecValueData];
20 [dt setObject:(id)kSecClassGenericPassword forKey:(id)kSecClass];
21
22 [dt setObject:@"Item label" forKey:(__bridge id)kSecAttrLabel];
23
24 [dt setObject:@"Item description" forKey:(__bridge id)kSecAttrDescription];
25
26 [dt setObject:@"Account" forKey:(__bridge id)kSecAttrAccount];
27
28 [dt setObject:@"Service" forKey:(__bridge id)kSecAttrService];
29
30 [dt setObject:@"Your comment here." forKey:(__bridge id)kSecAttrComment];
31 status = SecItemAdd((CFDictionaryRef)dt, NULL);
32 if(status==noErr)
33 {
34 NSLog(@"#######################save success");
35 return YES;
36 }
37 return YES;
38 }
39 else
40 if(status==errSecItemNotFound)
41 {
42 NSLog(@"#####################not found");
43 //store
44 NSMutableDictionary *dt = [[NSMutableDictionary alloc] init];
45 [dt setObject:@"label" forKey:(id)kSecAttrLabel];
46 [dt setObject:@"password" forKey:(id)kSecAttrService];
47 [dt setObject:[str dataUsingEncoding:NSUTF8StringEncoding] forKey:(id)kSecValueData];
48 [dt setObject:(id)kSecClassGenericPassword forKey:(id)kSecClass];
49
50 [dt setObject:@"Item label" forKey:(__bridge id)kSecAttrLabel];
51
52 [dt setObject:@"Item description" forKey:(__bridge id)kSecAttrDescription];
53
54 [dt setObject:@"Account" forKey:(__bridge id)kSecAttrAccount];
55
56 [dt setObject:@"Service" forKey:(__bridge id)kSecAttrService];
57
58 [dt setObject:@"Your comment here." forKey:(__bridge id)kSecAttrComment];
59 status = SecItemAdd((CFDictionaryRef)dt, NULL);
60 if(status==noErr)
61 {
62 NSLog(@"#######################save success");
63 return YES;
64 }
65 if(outDicRef)
66 CFRelease(outDicRef);
67 return NO;
68 }
69 else
70 {
71 NSLog(@"########################error query %d",status);
72 }
73 return NO;
74 }
代码有些凌乱，各位将就下吧，急着去睡觉~
读取代码如下：
1 - (NSString *)getData
2 {
3 OSStatus status = noErr;
4 NSMutableDictionary *query = [[NSMutableDictionary alloc] init];
5 [query setObject:(id)kSecClassGenericPassword forKey:(id)kSecClass];
6 /// query one
7 [query setObject:(id)kSecMatchLimitOne forKey:(id)kSecMatchLimit];
8 [query setObject:@"Service" forKey:(id)kSecAttrService];
9 ///如果想取到相关属性，这里必须设置。就这个地方，害我搞半天
10 [query setObject:(id)kCFBooleanTrue forKey:(id)kSecReturnAttributes];
11 CFDictionaryRef attributes = nil;
12 ///取到属性了
13 status = SecItemCopyMatching((__bridge CFDictionaryRef)query, (CFTypeRef *)&attributes);
14 if(status==noErr)
15 {
16 NSLog(@"--------%@",attributes);
17 }
18 [query removeObjectForKey:(id)kSecReturnAttributes];
19 CFDataRef outData;
20 ///取值，实际存放密码的地方，这里要设置
21 [query setObject:(id)kCFBooleanTrue forKey:(id)kSecReturnData];
22 status = SecItemCopyMatching((CFDictionaryRef)query, (CFTypeRef *)&outData);
23 ///解析回来
24 NSString *str = [[NSString alloc] initWithData:(__bridge NSData *)outData encoding:NSUTF8StringEncoding];
25 return str;
26 }
测试下：
取到属性：
取密码