Objective-C - Hello World app modification - iphone

Question

I'm just learning to do the "Hello, World" app. But I have a question. I'd like to change the code so the result reads "World, Hello" but can't figure out what I'm doing wrong.
Here's the original code:
- (IBAction)changeGreeting:(id)sender {
self.userName = self.textField.text;
NSString *nameString = self.userName;
if ([nameString length] == 0) {
nameString = #"World";
}
NSString *greeting = [[NSString alloc] initWithFormat:#"Hello, %#!", nameString];
self.label.text = greeting;
}
and I thought it would work if I could change it to:
- (IBAction)changeGreeting:(id)sender {
self.userName = self.textField.text;
NSString *nameString = self.userName;
if ([nameString length] == 0) {
nameString = #"World";
}
NSString *greeting = [[NSString alloc] initWithFormat:nameString , #"Hello, %#!"];
self.label.text = greeting;
}
However that still didn't work. What would I do to make that work?

Answer 1

Change this line
NSString *greeting = [[NSString alloc] initWithFormat:nameString , #"Hello, %#!"];
To
NSString *greeting = [[NSString alloc] initWithFormat:#"%#, Hello!", nameString];
initWithFormat, uses place holder when you write #"%#, Hello!" the "%#" indicates that the following string nameString will be replaced by it
So when we #"%#, Hello!" we really mean #"nameString, Hello!" (nameString in your example is World)