Check empty string in Swift

Question

In Objective C  one could do the following to check for strings   if   myString isEqualToString             NSLog   myString IS empty       else       NSLog   myString IS NOT empty  it is       myString       How does one detect empty strings in Swift

User · Answer

You can use this extension   extension String        static func isNilOrEmpty string  String   - gt  Bool           guard let value   string else   return true            return value trimmingCharacters in   whitespaces  isEmpty            and then use it like this   let isMyStringEmptyOrNil   String isNilOrEmpty string  myString

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Check  check for only spaces and newlines  characters in text  extension String       var  isBlank Bool           return self stringByTrimmingCharactersInSet NSCharacterSet whitespaceAndNewlineCharacterSet    isEmpty           using   if text isBlank       text is blank do smth

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There is now the built in ability to detect empty string with  isEmpty   if emptyString isEmpty       print  Nothing to see here       Apple Pre-release documentation   Strings and Characters

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You can also use an optional extension so you don t have to worry about unwrapping or using    true   extension String       var isBlank  Bool           return self trimmingCharacters in   whitespacesAndNewlines  isEmpty         extension Optional where Wrapped    String       var isBlank  Bool           if let unwrapped   self               return unwrapped isBlank           else               return true                     Note  when calling this on an optional  make sure not to use   or else it will still require unwrapping

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To do the nil check and length simultaneously  Swift 2 0 and iOS 9 onwards you could use  if yourString  characters count  gt  0

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isEmpty will do as you think it will  if string        it ll return true  Some of the other answers point to a situation where you have an optional string   PLEASE use Optional Chaining      If the string is not nil  isEmpty will be used  otherwise it will not   Below  the optionalString will NOT be set because the string is nil  let optionalString  String    nil if optionalString  isEmpty    true        optionalString    Lorem ipsum dolor sit amet      Obviously you wouldn t use the above code  The gains come from JSON parsing or other such situations where you either have a value or not  This guarantees code will be run if there is a value

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if myString  startIndex    myString  endIndex

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I am completely rewriting my answer  again   This time it is because I have become a fan of the guard statement and early return  It makes for much cleaner code  Non-Optional String Check for zero length  let myString  String    quot  quot   if myString isEmpty       print  quot String is empty  quot       return    or break  continue  throw       myString is not empty  if this point is reached  print myString   If the if statement passes  then you can safely use the string knowing that it isn t empty  If it is empty then the function will return early and nothing after it matters  Optional String Check for nil or zero length  let myOptionalString  String    nil  guard let myString   myOptionalString   myString isEmpty else       print  quot String is nil or empty  quot       return    or break  continue  throw       myString is neither nil nor empty  if this point is reached  print myString   This unwraps the optional and checks that it isn t empty at the same time  After passing the guard statement  you can safely use your unwrapped nonempty string

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Here is how I check if string is blank  By  blank  I mean a string that is either empty or contains only space newline characters   struct MyString     static func blank text  String  - gt  Bool       let trimmed   text trimmingCharacters in  CharacterSet whitespacesAndNewlines      return trimmed isEmpty         How to use   MyString blank         true

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In Xcode 11 3 swift 5 2 and later  Use  var isEmpty  Bool   get      Example  let lang    Swift 5   if lang isEmpty      print  Empty string       If you want to ignore white spaces  if lang trimmingCharacters in   whitespaces  isEmpty      print  Empty string

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What about  if let notEmptyString   optionalString where  notEmptyString isEmpty          do something with emptyString      NSLog  Non-empty string is      notEmptyString    else          empty or nil string     NSLog  Empty or nil string

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For optional Strings how about   if let string   string where  string isEmpty       print string

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public extension Swift Optional            func nonEmptyValue lt T gt  fallback  T  - gt  T                    if let stringValue   self as  String  stringValue isEmpty               return fallback                            if let value   self as  T               return value           else               return fallback

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I can recommend add small extension to String or Array that looks like   extension Collection       public var isNotEmpty  Bool           return  self isEmpty           With it you can write code that is easier to read   Compare this two lines  if  someObject someParam someSubParam someString isEmpty      and   if someObject someParam someSubParam someString isNotEmpty      It is easy to miss   sign in the beginning of fist line

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A concise way to check if the string is nil or empty would be   var myString  String    nil  if  myString        isEmpty       print  String is nil or empty

[swift] Check empty string in Swift?

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