作者:Mitchell 

• 先引入一段示例代码：

 - (void)viewDidLoad {
    [super viewDidLoad];
    //获取通讯录对象
    ABAddressBookRef addressBook = ABAddressBookCreateWithOptions(NULL, NULL);
    //获取通讯录对象汇总所有的联系人
    CFArrayRef peopleArray = ABAddressBookCopyArrayOfAllPeople(addressBook);
    //遍历数组
    CFIndex peopleCount = CFArrayGetCount(peopleArray);
    for (CFIndex i = 0; i<peopleCount; i++) {
        ABRecordRef person = CFArrayGetValueAtIndex(peopleArray, i);
        CFStringRef firstname = ABRecordCopyValue(person, kABPersonFirstNamePhoneticProperty);
        CFStringRef lastname = ABRecordCopyValue(person, kABPersonLastNamePhoneticProperty);
        NSString* firstName = (__bridge NSString*)firstname;
        NSString* lastName = (__bridge NSString*)lastname;        
        NSLog(@"%@%@",firstName,lastName);
        CFRelease(firstname);
        CFRelease(lastname);
    }
    CFRelease(peopleArray);
    CFRelease(addressBook);
}

• 在 iOS 中关于 CoreFoundation 框架和 Foundation 框架的桥接有三种方式。
  • 1、***CoreFoundation-> Foundation ***。
    将 CoreFoundation 框架的对象的对象所有权交给 Foundation 框架来使用，CoreFoundation 中的对象的内存管理还是自己来管理

(__bridge <#type#>)<#expression#>);

- 2、*** Foundation-> CoreFoundation ***。

将 Foundation 框架的对象 retain 之后转换为 CoreFoundation 框架来使用，这样保证了 Foundation 框架的对象被释放后，CoreFoundation 的值仍旧能正常使用：

(__bridge_retained <#CF type#>)<#expression#>;

- 3、*** CoreFoundation-> Foundation ***。

将 CoreFoundation 框架中的对象的所有权和内存都交给Foundation 框架来管理，也就是说通过这种方法来转换之后，不用写 CFRelease（） 了。

(__bridge_transfer <#Objective-C type#>)<#expression#>);

• 以示例代码为例：

 - (void)viewDidLoad {
    [super viewDidLoad];
    //获取通讯录对象
    ABAddressBookRef addressBook = ABAddressBookCreateWithOptions(NULL, NULL);
    //获取通讯录对象汇总所有的联系人
    CFArrayRef peopleArray = ABAddressBookCopyArrayOfAllPeople(addressBook);
    //遍历数组
    CFIndex peopleCount = CFArrayGetCount(peopleArray);
    for (CFIndex i = 0; i<peopleCount; i++) {
        ABRecordRef person = CFArrayGetValueAtIndex(peopleArray, i);
        CFStringRef firstname = ABRecordCopyValue(person, kABPersonFirstNamePhoneticProperty);
        CFStringRef lastname = ABRecordCopyValue(person, kABPersonLastNamePhoneticProperty);
//修改firstName的转换方式
        NSString* firstName = (__bridge_transfer NSString*)firstname;
        NSString* lastName = (__bridge NSString*)lastname;        
        NSLog(@"%@%@",firstName,lastName);
//就不用写这句话了
//CFRelease(firstname);
        CFRelease(lastname);
    }
    CFRelease(peopleArray);
    CFRelease(addressBook);
}