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# appending(_:)

Returns a new string made by appending a given string to the receiver.

```
func appending(_ aString: String) -> String
```

## Parameters

`aString`

The string to append to the receiver. This value must not be `nil`.
  
  > Important:
  > Raises an `NSInvalidArgumentException` if `aString` is `nil`.

## Return Value

A new string made by appending `aString` to the receiver.

## Discussion

This code excerpt, for example:

```objc
NSString *errorTag = @"Error: ";
NSString *errorString = @"premature end of file.";
NSString *errorMessage = [errorTag stringByAppendingString:errorString];
```

produces the string “`Error: premature end of file.`”.

## See Also

[`-  stringByAppendingFormat:`](/documentation/Foundation/NSString/stringByAppendingFormat:)

Returns a string made by appending to the receiver a string constructed from a given format string and the following arguments.


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