All Questions

1263
votes
18answers
316215 views

How can I disable ARC for a single file in a project?

I am using ARC successfully in my project. However, I have encountered a few files (e.g., in unit tests and mock objects) where the rules of ARC are a little more fragile right now. I recall hearing t...
1156
votes
19answers
162066 views

performSelector may cause a leak because its selector is unknown

I'm getting the following warning by the ARC compiler: "performSelector may cause a leak because its selector is unknown". Here's what I'm doing: [_controller performSelector:NSSelectorFromString(...
488
votes
11answers
103499 views

Should IBOutlets be strong or weak under ARC?

I am developing exclusively for iOS 5 using ARC. Should IBOutlets to UIViews (and subclasses) be strong or weak? The following: @property (nonatomic, weak) IBOutlet UIButton *button; Would get rid...
275
votes
4answers
149827 views

Objective-C declared @property attributes (nonatomic, copy, strong, weak)

Can someone explain to me in detail when I must use each attribute: nonatomic, copy, strong, weak, and so on, for a declared property, and explain what each does? Some sort of example would be great a...
199
votes
5answers
56454 views

How does the new automatic reference counting mechanism work?

Can someone briefly explain to me how ARC works? I know it's different from Garbage Collection, but I was just wondering exactly how it worked. Also, if ARC does what GC does without hindering perfor...
305
votes
7answers
88465 views

Shall we always use [unowned self] inside closure in Swift

In WWDC 2014 session 403 Intermediate Swift and transcript, there was the following slide The speaker said in that case, if we don't use [unowned self] there, it will be a memory leak. Does it mean...
73
votes
7answers
147562 views

Sending an HTTP POST request on iOS

I'm trying to send an HTTP Post with the iOS application that I'm developing but the push never reaches the server although I do get a code 200 as response (from the urlconnection). I never get a resp...
337
votes
7answers
173086 views

Objective-C ARC: strong vs retain and weak vs assign

There are two new memory management attributes for properties introduced by ARC, strong and weak. Apart from copy, which is obviously something completely different, are there any differences between...
172
votes
6answers
59218 views

Why is @autoreleasepool still needed with ARC?

For the most part with ARC (Automatic Reference Counting), we don't need to think about memory management at all with Objective-C objects. It is not permitted to create NSAutoreleasePools anymore, how...
217
votes
7answers
77550 views

How do I avoid capturing self in blocks when implementing an API?

I have a working app and I'm working on converting it to ARC in Xcode 4.2. One of the pre-check warnings involves capturing self strongly in a block leading to a retain cycle. I've made a simple code ...

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