My extensions to NSURLSession that handle data/text/json and throw exceptions

NSURLSessionExtension.swift

extension NSURLSession {
    
    enum UTF8Encoding : ErrorType { case Error }
    enum JsonDecoding : ErrorType { case Error }

    func dataForRequest(request:NSURLRequest, completeWith: (dataResult: () throws -> NSData) -> Void) {
        
        let task = self.dataTaskWithRequest(request) { (data:NSData?, response:NSURLResponse?, error:NSError?) in
            
            guard let data = data else {
                
                completeWith(dataResult: { throw error! } )
                return
            }
            
            completeWith(dataResult: { return data } )
        }
        
        task.resume()
    }

    func textForRequest(request:NSURLRequest, completeWith: (textResult: () throws -> String) -> Void) {
        
        let task = self.dataTaskWithRequest(request) { (data:NSData?, response:NSURLResponse?, error:NSError?) in
            
            guard let data = data else {
                
                completeWith(textResult: { throw error! } )
                return
            }
            
            completeWith(textResult: {
                
                guard let text = String(data: data, encoding: NSUTF8StringEncoding) else {
                    throw UTF8Encoding.Error
                }
                
                return text
            })
        }
        
        task.resume()
    }

    func jsonForRequest(request:NSURLRequest, completeWith: (jsonResult: () throws -> [String:AnyObject]) -> Void) {
        
        let task = self.dataTaskWithRequest(request) { (data:NSData?, response:NSURLResponse?, error:NSError?) in
            
            guard let data = data else {
                
                completeWith(jsonResult: { throw error! } )
                return
            }
            
            completeWith(jsonResult: {
                
                let json = try NSJSONSerialization.JSONObjectWithData(data, options: .AllowFragments) as? [String:AnyObject]
                
                if json == nil {
                    throw JsonDecoding.Error
                }
                
                return json!
            })
        }
        
        task.resume()
    }
    
    func awaitDataForRequest(request:NSURLRequest) throws -> NSData {
        
        let wait: dispatch_semaphore_t = dispatch_semaphore_create(0);
        var resData:NSData?
        var resError:NSError?
        
        let task = self.dataTaskWithRequest(request) { (data:NSData?, response:NSURLResponse?, error:NSError?) in
            
            resData = data
            resError = error
            
            dispatch_semaphore_signal(wait)
        }
        
        task.resume()
        
        dispatch_semaphore_wait(wait, DISPATCH_TIME_FOREVER)
        
        guard let data = resData else {
            throw resError!
        }
        
        return data
    }

    func awaitTextForRequest(request:NSURLRequest) throws -> String {
        
        let data = try self.awaitDataForRequest(request)
        
        guard let text = String(data: data, encoding: NSUTF8StringEncoding) else {
            throw UTF8Encoding.Error
        }
        
        return text
    }
    
    func awaitJsonWithRequest(request:NSURLRequest) throws -> [String:AnyObject] {
        
        let data = try self.awaitDataForRequest(request)
        
        let json = try NSJSONSerialization.JSONObjectWithData(data, options: .AllowFragments) as? [String:AnyObject]
        
        if json == nil {
            throw JsonDecoding.Error
        }
        
        return json!
    }
}