我试图从我的数据库中获取数据,但我有一个exc_bad_instruction在我的NSJSONSerialization。
func request(url:String, callback:(NSDictionary) -> ()){
let nsURL = NSURL(string: url)
let task = NSURLSession.sharedSession().dataTaskWithURL(nsURL!){
(data, response, error) in
//var error:NSError?
var response:NSDictionary
do{
response = try NSJSONSerialization.JSONObjectWithData(data!, options: NSJSONReadingOptions.MutableContainers) as! NSDictionary
callback(response)
}catch{
print("Something went wrong!")
}
}
task.resume()
}
你知道为什么它不工作吗?为了让你知道一些事情,我不得不从Swift 2开始使用do, try, catch,因为它之前工作得很好!
没有完整的错误消息,我们猜测关于确切的问题,但您应该针对错误的输入数据进行guard
:
func request(url:String, callback:(NSDictionary) -> ()){
let nsURL = NSURL(string: url)
guard nsURL != nil else {
print("URL not valid: (url)")
return
}
let task = NSURLSession.sharedSession().dataTaskWithURL(nsURL!){
(data, response, error) in
guard data != nil else {
print("dataTaskWithURL failed: (error)")
return
}
do {
if let response = try NSJSONSerialization.JSONObjectWithData(data!, options: []) as? NSDictionary {
callback(response)
} else {
print("JSON parsing succeeded, but cast to dictionary failed")
}
} catch let parseError {
print("Something went wrong: (parseError)")
}
}
task.resume()
}
do
- try
- catch
捕获错误,而不是异常,因此您必须自己测试有效URL和有效NSData
。此外,避免强制展开可选(例如!
),特别是当它是一个合理的运行时错误(例如没有网络)时。请使用可选绑定。