Week 1 Questions and Answers

Question: When should I explicitly write strong vs. weak when declaring properties in class interfaces?

In other words, what is the difference between

@property (strong, nonatomic) NSString *name;


@property (nonatomic) NSString *name;


And when do I use:

@property (weak, nonatomic) NSString *name;

Answer: I found the answer on Ry’s Objective-C Tutorial, which I think is an amazing reference, because it’s very well organized and comprehensive.

In short,

@property (strong, nonatomic) NSString *name;


@property (nonatomic) NSString *name;

are equivalent. However, the first version is better, because there is no doubt. (Learning iOS Development by Maurice Sharp et al. p.79)

An example of when to use weak is when two objects have each other in their properties.

A Person may have a

@property Computer *myComputer;

and a computer may have a

@property Person *owner;

but you would not want to have both properties be strong because it would cause a memory leak (the program will use memory and not give up the memory, slowing down the phone).

In this case, I would make the owner weak because the parent object is the Person and not the computer.

@property (weak) Person *owner;

Question: If I clone a branch from Github and the branch that I wanted was not moved to my local machine, what should I do to get that branch from the remote? 

Answer: git checkout -t origin/<branch name>


//Should I use
[NSMutableArray new];
[[NSMutableArray alloc] init];

Answer: It’s up to you. The latter is more consistent because sometimes you might

[[NSMutableArray alloc] initWithArry:newArray];


//Should I use
[newString length];

Answer: Dot notation is more readable, but opinions may differ, sometimes within the same person. Ex.

Dot notation in Objective-C: 100% Pure Evil

In Which I Embrace Dot Notation

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s