初始化CGContext上

Question

我想初始化CGContext上（API）

let documentsPath = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)[0] 
let url = NSURL.fileURL(withPath: documentsPath + "/datafile") 
if let context = CGContext(url: url as CFURL) { 
    // stuff  
} 

但是，這給我的錯誤：

Cannot invoke initializer for type 'CGContext' with an argument list of type '(url: CFURL)'

我也試過CGContext(url as CFURL)以及CGContext.init(url as CFURL)

如果我加mediaBox: nil我得到： Ambiguous reference to member 'init(data:width:height:bitsPerComponent:bytesPerRow:space:bitmapInfo:releaseCallback:releaseInfo:)

Answer 1

let url = NSURL.fileURL(withPath: documentsPath + "/datafile") as CFURLRef  
let context = CGPDFContextCreateWithURL(url, nil, nil)