Here are some useful macros around NSLog I use a lot: #ifdef DEBUG # define DLog(fmt, …) NSLog((@”%s [Line %d] ” fmt), __PRETTY_FUNCTION__, __LINE__, ##__VA_ARGS__) #else # define DLog(…) #endif // ALog always displays output regardless of the DEBUG setting #define ALog(fmt, …) NSLog((@”%s [Line %d] ” fmt), __PRETTY_FUNCTION__, __LINE__, ##__VA_ARGS__) The DLog macro is … Read more
The generally-preferred code for 10.5+/iOS. for (id object in array) { // do something with object } This construct is used to enumerate objects in a collection which conforms to the NSFastEnumeration protocol. This approach has a speed advantage because it stores pointers to several objects (obtained via a single method call) in a buffer … Read more
@synthesize will generate getter and setter methods for your property. @dynamic just tells the compiler that the getter and setter methods are implemented not by the class itself but somewhere else (like the superclass or will be provided at runtime). Uses for @dynamic are e.g. with subclasses of NSManagedObject (CoreData) or when you want to … Read more
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
The original code for the Cocoa frameworks came from the NeXTSTEP libraries Foundation and AppKit (those names are still used by Apple’s Cocoa frameworks), and the NextStep engineers chose to prefix their symbols with NS. Because Objective-C is an extension of C and thus doesn’t have namespaces like in C++, symbols must be prefixed with … Read more
A quick summary of the concepts: Hugging => content does not want to grow Compression Resistance => content does not want to shrink Example: Say you’ve got a button like this: [ Click Me ] and you’ve pinned the edges to a larger superview with priority 500. Then, if Hugging priority > 500 it’ll look … 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
An Objective-C delegate is an object that has been assigned to the delegate property another object. To create one, you define a class that implements the delegate methods you’re interested in, and mark that class as implementing the delegate protocol. For example, suppose you have a UIWebView. If you’d like to implement its delegate’s webViewDidStartLoad: … 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
You may have a bad connection in your xib. I’ve had this error many times. While TechZen’s answer is absolutely right in this case, another common cause is when you change the name of a IBOutlet property in your .h/.m which you’ve already connected up to File’s Owner in the nib. From your nib: Select … Read more