Swift如何比较来自NSString的字符串

Question

I get a return number(0 for success, 1 for failure) form sever made by php so I want get this number to judge my operation succeeded or not. I use this :

var str1 :String = NSString(data: d, encoding: NSUTF8StringEncoding)!
let str2 = "1"
println(str1) // output is 1
println(str2) // output is 1

if(str1==str2){println("same")} //but the two is not same

so I debug for this and I get this result: //str1 _countAndFlags UWord 13835058055282163717 -4611686018427387899 //str2 _countAndFlags UWord 1 1

And I try to use toInt. I get 1383... form str3 and 1 form str4 So how can I do to solve this problem. Thank you very much.

Answer 1

It sounds like you have some whitespace in your string. To spot this using println , you could try println(",".join(map(str1,toString))) . If you see any commas at all, that's the problem.

The easiest way to fix this (it may be better to kill the whitespace at the source) is to use stringByTrimmingCharactersInSet :

let str1: String = NSString(data: d, encoding: NSUTF8StringEncoding)
                   ?.stringByTrimmingCharactersInSet(
                     NSCharacterSet.whitespaceAndNewlineCharacterSet())
let str2 = "1"
if str1==str2 { println("same") }

Note a few other changes:

• let rather than var since it doesn't look like you need to change str1 after it's declared
• No force-unwrap ( ! ) at the end of the creation of the NSString . Never force-unwrap something that might be nil, you will get a runtime error!
• ?. to optionally call the trim if it isn't nil.

Note, this means str1 is a String? not a String but that's fine since you can compare optionals with non-optionals (they'll be equal if the optional contains a value equal to the non-optional, but not if the optional contains nil )

If what you actually want is an Int , just add a let int1 = str1?.toInt() . This will still be an optional – if there is a reasonable default in case of nil , you could do let int1 = str1?.toInt() ?? 0 let int1 = str1?.toInt() ?? 0 and it will be non-optional with a value of 0 in case of nil .

Answer 2

在swift 2中，可以使用let str = "string" let nsstr:NSString = "string" if nsstr.containsString(str){ print(true) }else{ print(false) }对我let str = "string" let nsstr:NSString = "string" if nsstr.containsString(str){ print(true) }else{ print(false) }