Building 3 methods in Objective C - objective-c

Question

I'm having trouble with a school problem in Objective C. I need to build 3 methods. The first method tells you if someone is in a line. If nobody is in the line it tells you nobody is in the line otherwise it tells you who is in the line and it lists the names on a new line.
The second method adds names to the line.
The third method removes a name from the line and tells you who was removed.
First method:
-(NSString*)stringWithDeliLine:(NSArray*) deliLine{
NSString *empty = #"The line is currently empty.";
//Some kind of formatted string
if(deliLine == nil || [deliLine count] == 0)
{
empty;
}
else
{
//formatted string
}
//not sure how to return either empty or formatted string
}
Second Method:
-(void)addName:toDeliLine:(NSString*)name:(NSMutableArray*)deliLine{
[deliLine addObject:name];
}
The third method I was going to use removeObject but the instructions said not to use it so I have no idea where to start.I have the signature I think.
-(NSString*)serveNextCustomerInDeliLine:(NSMutableArray*)deliLine{
return nil;
}
For the first method I'm not sure why my literal string won't work in the if statement. I thought I was saying look at the array if nothing is in the array then it's the first object and show the string literal. else show some kinda of formatted string. I've tried all kinds of strings but none seem to be working so that's why I have the comment formatted string. If someone could give me a hint that would be great. I don't need the answer just a clue on what to think about. This is long post sorry.

Answer 1

A possible implementation can be the following. Please note that I have not testes edge cases and I wrote the code without Xcode support
#import <Foundation/Foundation.h>
#interface Line : NSObject
- (NSString*)printLine;
- (void)addCustomer:(NSString*)customer;
- (NSString*)removeCustomer:(NSString*)customer;
#end
#import "Line.h"
#interface Line ()
#property (nonatomic, strong, readwrite) NSMutableArray<NSString*> *customers;
#end
#implementation Line
- (instancetype)init {
self = [super init];
if (self) {
_customers = [NSMutableArray array];
}
return self;
}
- (NSString*)printLine {
NSUInteger count = self.customers.count;
if(count == 0) {
return #"Empty";
}
NSMutableString *descr = [NSMutableString string];
for (NSString *customer in self.customers) {
[descr appendString:[NSString stringWithFormat:#"%# ", customer]];
}
return [descr copy];
}
- (void)addCustomer:(NSString*)customer {
[self.customers addObject:customer];
}
- (NSString*)removeCustomer:(NSString*)customer {
NSUInteger index = [self.customers indexOfObject:customer];
if(index == NSNotFound) {
return [NSString stringWithFormat:#"%# not removed", customer];
}
NSString *removedCustomer = [self.customers objectAtIndex:index];
[self.customers removeObjectAtIndex:index];
return removedCustomer;
}
#end
Usage:
Line *line = [[Line alloc] init];
[line addCustomer:#"customer"];
NSLog(#"%#", [line printLine]);
NSLog(#"%#", [line removeCustomer:#"customer"]);
NSLog(#"%#", [line printLine]);

Answer 2

Edit:
I've updated my answer, passing the array as a parameter is not necessary, just initialize deliLine as a mutable array property.
For you first method, you could do the following,
- (NSString *)deliLineContents {
NSString *empty = #"The line is currently empty.";
NSMutableString *namesInQueue = [[NSMutableString alloc] init];
if(self.deliLine == nil || [self.deliLine count] == 0) {
return empty;
} else {
// Loop through your array and return a string of all the names
for (NSString *string in self.deliLine ) {
[namesInQueue appendString:string];
}
}
return [NSString stringWithString:namesInQueue];
For your second method, you're already pretty much there, maybe look up how to construct method signatures.
- (void)addNameToDeliLine:(NSString*)name {
[self.deliLine addObject:name];
}
For your third method, not sure if this meets your requirement, if not let me know.
- (NSString *)customerRemovedFromLine {
// I've making an assumption that you want to remove the first customer
NSString *servedCustomer = [self.deliLine objectAtIndex:0];
[self.deliLine removeObjectAtIndex:0];
return servedCustomer;
}
You probably don't need to pass deliLine around, just create it as a property and access it with self.deliLine. Anyway hope this helps, good luck.