For attributes whose type is an immutable value class that conforms to the NSCopying protocol, you almost always should specify copy in your @property declaration. Specifying retain is something you almost never want in such a situation. Here’s why you want to do that: NSMutableString *someName = [NSMutableString stringWithString:@”Chris”]; Person *p = [[[Person alloc] init] … Read more
Switch to Header/Source File Option ⌥ Command ⌘ Up Arrow ↑ View > Switch to Header/Source File Switches between the .m and .h files. In Xcode 4 this is ctrl Command ⌘ Up Arrow ↑
Firstly I’d like to draw your attention to the Cocoa/CF documentation (which is always a great first port of call). The Apple docs have a section at the top of each reference article called “Companion Guides”, which lists guides for the topic being documented (if any exist). For example, with NSTimer, the documentation lists two … Read more
There are a few things I have started to do that I do not think are standard: 1) With the advent of properties, I no longer use “_” to prefix “private” class variables. After all, if a variable can be accessed by other classes shouldn’t there be a property for it? I always disliked the … Read more
objectForKey: is an NSDictionary method. An NSDictionary is a collection class similar to an NSArray, except instead of using indexes, it uses keys to differentiate between items. A key is an arbitrary string you provide. No two objects can have the same key (just as no two objects in an NSArray can have the same … Read more
There isn’t, as others have already said, such a thing as a private method in Objective-C. However, starting in Objective-C 2.0 (meaning Mac OS X Leopard, iPhone OS 2.0, and later) you can create a category with an empty name (i.e. @interface MyClass ()) called Class Extension. What’s unique about a class extension is that … Read more
I reproduced your setup both with your data model and one of my own with different names. I got the same error in both cases. Looks like a bug in Apple’s autogenerated code.
NSArray *array = [mutableArray copy]; Copy makes immutable copies. This is quite useful because Apple can make various optimizations. For example sending copy to a immutable array only retains the object and returns self. If you don’t use garbage collection or ARC remember that -copy retains the object.
You can try this: NSLog(@”%@”, NSStringFromCGPoint(cgPoint)); There are a number of functions provided by UIKit that convert the various CG structs into NSStrings. The reason it doesn’t work is because %@ signifies an object. A CGPoint is a C struct (and so are CGRects and CGSizes).
I use [NSException raise:format:] as follows: [NSException raise:@”Invalid foo value” format:@”foo of %d is invalid”, foo];