NSData won't accept valid base64 encoded string

Your Base64 string is not valid. It must be padded with = characters to havea length that is a multiple of 4. In your case: "eyJlbWFp....MTM3fQ==".

With this padding, initWithBase64EncodedString decodes the Base64 string correctly.

Although Martin's answer is correct, here is a quick and correct(!) way to fix the problem:

NSString *base64String = @"<the token>";NSUInteger paddedLength = base64String.length + (4 - (base64String.length % 4));NSString* correctBase64String = [base64String stringByPaddingToLength:paddedLength withString:@"=" startingAtIndex:0];

Here is a solution that pads the Base-64 string appropriately and works in iOS 4+:

NSData+Base64.h

@interface NSData (Base64)/** Returns a data object initialized with the given Base-64 encoded string. @param base64String A Base-64 encoded NSString @returns A data object built by Base-64 decoding the provided string. Returns nil if the data object could not be decoded. */- (instancetype) initWithBase64EncodedString:(NSString *)base64String;/** Create a Base-64 encoded NSString from the receiver's contents @returns A Base-64 encoded NSString */- (NSString *) base64EncodedString;@end

NSData+Base64.m

@interface NSString (Base64)- (NSString *) stringPaddedForBase64;@end@implementation NSString (Base64)- (NSString *) stringPaddedForBase64 {    NSUInteger paddedLength = self.length + (self.length % 3);    return [self stringByPaddingToLength:paddedLength withString:@"=" startingAtIndex:0];}@end@implementation NSData (Base64)- (instancetype) initWithBase64EncodedString:(NSString *)base64String {    return [self initWithBase64Encoding:[base64String stringPaddedForBase64]];}- (NSString *) base64EncodedString {    return [self base64Encoding];}@end