NSLocalizedString奇怪的警告

#import <Foundation/Foundation.h>

@interface NSString (Localize)
@end

@implementation NSString (Localize)

- (NSString *)localizedStringForKey:(NSString *)key locale:(NSLocale *)locale {
    return NSLocalizedString(key, [locale localeIdentifier], [locale userInfo]);
}

@end

int main(int argc, const char *argv[]) {
    @autoreleasepool {
        NSLocale *locale = [NSLocale localeWithLocaleIdentifier:@"en_US"];
        NSString *str = @"Hello World";
        NSString *localizedStr = [str localizedStringForKey:@"Hello" locale:locale];
        NSLog(@"%@", localizedStr);
    }
    return 0;
}