在Objective C上運行shell命令並同時獲得輸出

Question

假設我想通過Objective C應用運行curl -o http://example.com/file.zip，並且我希望有一個標籤或文本框，其中包含在命令運行時更新的下載狀態。也許這可以使用dispatch_async來實現，但現在確定如何。在標記爲重複之前，我找到的方法運行命令，並在完成後獲得輸出結果。我想在運行時得到輸出，就像終端模擬器一樣。

Answer 1

您需要使用standardOutput屬性連接NSPipe到NSTask和註冊接收數據可用通知。

@interface TaskMonitor: NSObject 
@property NSPipe *outputPipe; 
@end 

@implementation TaskMonitor 

-(void)captureStandardOutput:(NSTask *)process { 

    self.outputPipe = [NSPipe new]; 
    process.standardOutput = self.outputPipe; 

    //listen for data available 
    [self.outputPipe.fileHandleForReading waitForDataInBackgroundAndNotify]; 

    [[NSNotificationCenter defaultCenter] addObserverForName:NSFileHandleDataAvailableNotification object:self.outputPipe.fileHandleForReading queue:nil usingBlock:^(NSNotification * _Nonnull note) { 

    NSData *output = self.outputPipe.fileHandleForReading.availableData; 
    NSString *outputString = [[NSString alloc] initWithData:output encoding:NSUTF8StringEncoding]; 

    dispatch_async(dispatch_get_main_queue(), ^{ 
     // do something with the string chunk that has been received 
     NSLog(@"-> %@",outputString); 
    }); 

    //listen again... 
    [self.outputPipe.fileHandleForReading waitForDataInBackgroundAndNotify]; 

    }]; 

} 

@end