HowToCreateTollFreeBridgedClass

经常看到toll free bridged，只是大概知道是类型可以相互转换。为了更好的了解，在网上找到了这个资料。保存下来，方便以后查看



http://www.cocoadev.com/index.pl?HowToCreateTollFreeBridgedClass



The following classes are toll-free bridged:

http://www.cocoadev.com/index.pl?TollFreeBridged

NSArray = CFArray

NSMutableArray = CFMutableArray?

NSCalendar = CFCalendar?

NSCharacterSet = CFCharacterSet?

NSMutableCharacterSet? = CFMutableCharacterSet?

NSData = CFData?

NSMutableData = CFMutableData?

NSDate = CFDate?

NSDictionary = CFDictionary

NSMutableDictionary = CFMutableDictionary?

NSNumber = CFNumber

NSTimer = CFRunLoopTimer?

NSSet = CFSet?

NSMutableSet = CFMutableSet?

NSString = CFString

NSMutableString = CFMutableString?

NSUrL = CFURL

NSTimeZone? = CFTimeZone?

NSInputStream? = CFReadStream?

NSOutputStream? = CFWriteStream?

Disc Recording

DRBurn = DRBurnRef?

DRErase = DREraseRef?

DRDevice = DRDeviceRef?

DRTrack = DRTrackRef?

DRFile? = DRFileRef?

DRFolder? = DRFolderRef? (starting with 10.3)

NSAttributedString = CFAttributedString?

NSMutableAttributedString = CFMutableAttributedString?

The following classes are not toll-free bridged:

NSBundle and CFBundle?

NSHost and CFHost

NSRunLoop and CFRunLoop?

NSNotificationCenter and CFNotificationCenter?

NSSocket? and CFSocket

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TollFreeBridging is what allows you to take CoreFoundation types and typecast them to Cocoa types (and vice versa).

So, if you have to call a CoreFoundation function that takes a CFString, but you have an NSString, you can just pass it your NSString with:

CFStringRef myCFString = (CFStringRef)someNSString;

And if you need to get an NSString from a CFString, you can do this:

NSString* myNSString = (NSString*)someCFString;

see also: HowToCreateTollFreeBridgedClass

See which classes are TollFreeBridged.