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In just three months, Punch did the impossible for our product team: they moved mountains.

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Head of Product of 1-Page

If you want real development that works and effective implementation — Punch’s got you covered.

Justin Grant

Founder of ScrubPay

Thanks dude. You’re saving my butt more than you could ever imagine #blessed #myhero.

Arash Namvar

Engineer at FogHorn Systems

Punch enabled us to deliver on time and they’ve been heavy hitters in our corner since.

David Sanghera

Head of Product of 1-Page

Very very happy to have Punch on the team.

Joanna Weidenmiller

CEO of 1-Page

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Hans Stier

CEO of Bonaverde

Punch delivers, plain and simple.

James Gutierrez

Founder of Insikt

Delivered an excellent engineer who is doing great work.

Nathan Beckord

CEO of Foundersuite

Punch took the time to understand our needs — both on the technical side, and on the company culture side —

Nathan Beckord

CEO of Foundersuite

Our checkout UX is basically 5 years in the future now

Noah Ready-Campbell

CEO of Twice

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Objective-C interview questions

The most popular questions

Use our complementary questions and answers to filter and hire the best. Questions crowdsourced by our clients, answers by Punch. We provide these complementary questions to help our clients more quickly create tests for potential hires at their organizations.

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Punch offers four divisions of services: design, engineering, staffing, and demand

Interview questions for your next interview

Question
What is difference between NSArray and NSMutableArray in Objective C?
Answer
Mutable means you can change its contents later, Immutable means once they are initialized, their values cannot be changed. So we cannot change NSArray's value after its initialization.
Question
Whats the difference between frame and bounds?
Answer
The frame is the rectangle that defines the UIView with respect to its superview. The bounds of an UIView is the rectangle that is relative to its own coordinate system.

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Questions
By writing code show how can we achieve singleton pattern in Objective C?
Answer
+ (id)sharedObject {
static id shared;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
shared = [[self alloc] init];
});
return shared;
}
Questions
What is atomic and nonatomic? Which one is default?
Answer
You can use this attribute to specify that accessor methods are not atomic. It will ensure the present process is completed by the CPU, before another process accesses the variable. nonatomic specifies that accessors are nonatomic. It is faster and not thread-safe.

By default, accessors are atomic.
Questions
What does the following line says about my Object?id myObject;
Answer
It says that myObject conforms to the Painting protocol.
Questions
How can you declare a method, that can be set as the action to be performed on various events?
Answer
— (IBAction) action:(id) sender;
Questions
Write a function that will take date as NSString and converts it to NSDate object.
Answer
-(NSDate*)stringToDate:(NSString*)dateString{
NSDateFormatter *dateFormat = [[NSDateFormatter alloc] init];
[dateFormat setDateFormat:@"yyyy-MM-dd"];
NSDate *date = [dateFormat dateFromString:dateString];
return date;
}
Questions
Calculate total number of words and character in a given NSString.
Answer
NSString *text = @“Hello World“;

NSArray *words = [text componentsSeparatedByCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
NSInteger wordCount = [words count];

NSInteger characterCount = 0;
for (NSString *word in words) {
characterCount += [word length];
}
Questions
Sort a NSMutableArray with custom objects in it. (Assume custom array have type Person objects, sort these according to their date of birth)
Answer
NSArray *sortedArray;
sortedArray = [originalArray sortedArrayUsingComparator:^NSComparisonResult(id a, id b) {
NSDate *first = [(Person*)a birthDate];
NSDate *second = [(Person*)b birthDate];
return [first compare:second];
}];

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