如何將數據轉換爲JPEG格式？

Question

我有這樣的代碼：

NSImage * strImage = [[NSImage alloc]initWithContentsOfFile:ImageFilePath] ; 
NSData *imageData = [strImage TIFFRepresentation]; 

什麼我需要是的imageData轉換爲JPEG格式。我希望它能像QImage save()一樣工作。

所以，你可以看到如何save()作品中，我會給你一個鏈接： http://doc.qt.nokia.com/4.6/qimage.html#save

請幫助我。

Answer 1

從CocoaDev ...如果你創建後做了什麼NSImage：

NSData *imageData = [image TIFFRepresentation]; 
NSBitmapImageRep *imageRep = [NSBitmapImageRep imageRepWithData:imageData]; 
NSNumber *compressionFactor = [NSNumber numberWithFloat:0.9]; 
NSDictionary *imageProps = [NSDictionary dictionaryWithObject:compressionFactor 
             forKey:NSImageCompressionFactor]; 
imageData = [imageRep representationUsingType:NSJPEGFileType properties:imageProps]; 
[imageData writeToFile:filename atomically:YES]; 

如果你不會做其他任何與NSImage前：

NSArray *representations = [myImage representations]; 
NSNumber *compressionFactor = [NSNumber numberWithFloat:0.9]; 
NSDictionary *imageProps = [NSDictionary dictionaryWithObject:compressionFactor 
             forKey:NSImageCompressionFactor]; 
NSData *bitmapData = [NSBitmapImageRep representationOfImageRepsInArray:representations 
             usingType:NSJPEGFileType 
             properties:imageProps];  
[bitmapData writeToFile:filename atomically:YES];