NSString : easy way to remove UTF-8 accents from a string?

NSString *str = @"Être ou ne pas être. C'était là-bas.";
NSData *data = [str dataUsingEncoding:NSASCIIStringEncoding allowLossyConversion:YES];
NSString *newStr = [[NSString alloc] initWithData:data encoding:NSASCIIStringEncoding];
NSLog(@"%@", newStr);

... or try using NSUTF8StringEncoding instead.

List of encoding types here:

https://developer.apple.com/documentation/foundation/nsstringencoding

---

Just FTR here's a one line way to write this great answer:

yourString = [[NSString alloc]
  initWithData:
    [yourString dataUsingEncoding:NSASCIIStringEncoding allowLossyConversion:YES]
  encoding:NSASCIIStringEncoding];

Mattt Thompson covered this in NSHipster and again at WWDC 2013 session 228

TL;DR

NSMutableString *str = [@"Être ou ne pas être. C'était là-bas." mutableCopy];
CFStringTransform((__bridge CFMutableStringRef)string, NULL, kCFStringTransformStripCombiningMarks, NO);

Should do the trick, it worked great for me.

Caveat Since a lot of people in the comments say this should be the accepted answer I want to give a caveat for this method. This method is pretty damn slow and should be used with care if huge amounts of string/data needs to be transformed

Have you tried

[string stringByFoldingWithOptions:NSDiacriticInsensitiveSearch locale:[NSLocale currentLocale]]

or

Boolean CFStringTransform (
   CFMutableStringRef string,
   CFRange *range,
   CFStringRef transform,
   Boolean reverse
);

?

CFStringTransform & Transform Identifiers

NSMutableString *string = ...;
CFMutableStringRef stringRef = (__bridge CFMutableStringRef)string;
CFStringTransform(stringRef, NULL, kCFStringTransformToLatin, NO);
NSLog(@"%@", string);

Just an update to say that it can be done like that in swift:

"Être ou ne pas être. C'était là-bas.".stringByFoldingWithOptions(NSStringCompareOptions.DiacriticInsensitiveSearch, locale: NSLocale.currentLocale())

--> "Etre ou ne pas etre. C'etait la-bas."