iphone下json的解析 NSJSONSerialization

- (IBAction)JOSNButtonPressed:(id)sender {

    NSString *str=[@"https://douban.fm/j/mine/playlist?type=n&h=&channel=0&from=mainsite&r=4941e23d79" stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];