以下是如何执行此操作的示例:

Here is an example of how you can do it:

int main (int argc, const char * argv[]) {
    NSString *str = @"Hello";
    int add = 8-[str length];
    if (add > 0) {
        NSString *pad = [[NSString string] stringByPaddingToLength:add withString:@" " startingAtIndex:0];
        str = [pad stringByAppendingString:str];
    }
    NSLog(@"'%@'", str);
    return 0;
}