what happens when stringWithFormat format has no type placeholders but has arguments

Question

Suppose I have a method like this

+ (NSString *)stringWithObject:(id)object format:(NSString *)format
{
    NSString *string = [NSString stringWithFormat:format, object];

    NSLog(@"%@", string);

    return string;
}

The object parameter is never nil but the format argument passed into the method might either be

NSString *formatWithPlaceholder = @"object: %@"

or

NSString *formatWithoutPlaceholder = @"No object";

so if formatWithoutPlaceholder is passed into the method as the format argument, the console output is correct and there are no warnings or errors, but will this cause other problems? I feel like there is something wrong about the usage of stringWithFormat: like this.

Answer 1

Nothing bad happens when the format string has fewer format specifiers than the number of parameters supplied: your code is valid for both format strings.

However, when the opposite situation happens (more format specifiers than the parameters) you get undefined behavior.