The reason why == works is because of pointer comparison. When you define a constant NSString using @””, the compiler uniquifies the reference. When the same constants are defined in other places in your code, they will all point to the same actual location in memory. When comparing NSString instances, you should use the isEqualToString: … Read more
Although Core Data is a descendant of Apple’s Enterprise Object Framework, an object-relational mapper (ORM) that was/is tightly tied to a relational backend, Core Data is not an ORM. It is, in fact, an object graph management framework. It manages a potentially very large graph of object instances, allowing an app to work with a … Read more
Check out my NSString category for HTML. Here are the methods available: – (NSString *)stringByConvertingHTMLToPlainText; – (NSString *)stringByDecodingHTMLEntities; – (NSString *)stringByEncodingHTMLEntities; – (NSString *)stringWithNewLinesAsBRs; – (NSString *)stringByRemovingNewLinesAndWhitespace;
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.
The bounds of an UIView is the rectangle, expressed as a location (x,y) and size (width,height) relative to its own coordinate system (0,0). The frame of an UIView is the rectangle, expressed as a location (x,y) and size (width,height) relative to the superview it is contained within. So, imagine a view that has a size … Read more
You can use NSTask. Here’s an example that would run ‘/usr/bin/grep foo bar.txt‘. int pid = [[NSProcessInfo processInfo] processIdentifier]; NSPipe *pipe = [NSPipe pipe]; NSFileHandle *file = pipe.fileHandleForReading; NSTask *task = [[NSTask alloc] init]; task.launchPath = @”/usr/bin/grep”; task.arguments = @[@”foo”, @”bar.txt”]; task.standardOutput = pipe; [task launch]; NSData *data = [file readDataToEndOfFile]; [file closeFile]; NSString *grepOutput … Read more
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
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
If you see this warning: warning: receiver ‘MyCoolClass’ is a forward class and corresponding @interface may not exist you need to #import the file, but you can do that in your implementation file (.m), and use the @class declaration in your header file. @class does not (usually) remove the need to #import files, it just … Read more
You should create a header file like: // Constants.h FOUNDATION_EXPORT NSString *const MyFirstConstant; FOUNDATION_EXPORT NSString *const MySecondConstant; //etc. (You can use extern instead of FOUNDATION_EXPORT if your code will not be used in mixed C/C++ environments or on other platforms.) You can include this file in each file that uses the constants or in the … Read more