book info
"Programming in Objective-C", Stephen G. Kochan, ISBN 0-672-32586-1
http://www.kochan-wood.com - examples.
http://www.cocoadevcentral.com, http://www.cocoadev.com
memory management
autorelease pool, object "init", "retain", "autorelease", "dealloc" methods. override "dealloc" to do custom release stuff.
categories, protocols, posing
Categories and posing share much in common. When overriding a method in category, you cannot access the original. When posing, you are still acting as a subclass, so you can call super methods.
"Add a category called TempFiles to NSString and define a method that returns a temporary file name":
@interface NSString (TempFiles)
-(NSString *) temporaryFileName;
@end
@implementation NSString (TempFiles)
-(NSString *) temporaryFileName {
return [[NSTemporaryDirectory() stringByAppendingString:@"/"]
stringByAppendingString: [[NSProcessInfo processInfo] globallyUniqueString]];
}
@end
A protocol is a list of methods that is shared among classes.
#interface AddressBook: NSObject <NSCopying, NSCoding>
"I am Addressbook class, based on NSObject, and I implement the NSCopying and NSCoding protocols."
Informal protocols - really no more than a grouping of methods under a name.
Composite objects - objects that have another object as their instance variable, piggybacking on its methods.
C features - variables, pointers
struct packedStruct {
unsigned int f1:1;
unsigned int f2:1;
unsigned int type:4;
unsigned int index:9;
}
This is a bit field, the number after colon shows number of bits. Useful for flags.
(*x).y is the same as x->y
- int *valuesPtr;
valuesPtr = values; or valuesPtr = &values[0];
- now *(valuesPtr+i) accesses values[i].
Pointers to functions - useful for dispatch tables and passing to methods.
Union - like a struct, but from storage POV only one member is "active" at a time, can store alternate data types in same memory space.
foundation - strings
NSLog(@"%@", anyVariable)
Dump any variable to console.
NSRange - type with ".location" and ".length", used as input when getting substrings as returned from substring search
foundation - basic data storage/manipulation objects
Each of these also has a Mutable subclass.
- NSArray - array
- NSDictionary - key-value
- NSSet - unique objects
- NSCountedSet - more than one of the same object with counts.
object copying - mutableCopy method. Need to release myself if creating object with methods "alloc", "copy", "allocWithZone:", "copyWithZone:" or "mutableCopy".
Shallow (default) vs deep copying. <NSCopying> protocol. Make copy of parameter/instance variables in setter/getter methods.
"nil" - invalid object.
archiving, plists
property list: disk-dumped version of "property list objects" (NSString, NSData, NSArray, or NSDictionary objects, or also NSNumber or NSData). Keys in dictionary must be NSString objects.
writeToFile: and blaahWithContentsOfFile: methods.
NSCopying protocol for archiving. NSKeyedArchiver. Use archiver to deep copy objects. Following is useful to deep copy an object or copy an object who doesn't support the NSCoding protocol.
dataArray2 = [NSUnarchiver unarchiveObjectWithData:
[NSArchiver archivedDataWithRootObject: dataArray]];