CS 696 Mobile Application DevelopmentFall Semester, 2010Doc 2 Objective C - BasicsAug 31, 2010Copyright ©, All rights reserved. 2010 SDSU & Roger Whitney, 5500 Campanile Drive, San Diego, CA 92182-7700 USA. OpenContent (http://www.opencontent.org/openpub/) license defines the copyright on this document.References2The Objective-C 2.0 Programming Language, http://developer.apple.com/iphone/library/documentation/Cocoa/Conceptual/ObjectiveC/Introduction/introObjectiveC.html#//apple_ref/doc/uid/TP30001163Objective-C Hello World3#import <Cocoa/Cocoa.h>int main(int argc, char *argv[]){ NSLog(@"Hello World!"); return 0; }History4Early 1980'sBrad Cox & Tom Love combine C and Smalltalk messagingGoal - software components1986 - Objective-C book published1988 - NeXT uses Objective-C to implement NeXTstep user interface1996 - Apple purchase NeXT, Objective-C becomes bases for Mac OS X 2007 - iPhone OS written in Objective-C2010 Aug - TIOBE index ranks Objective-C 9'th in popularityTIOBE programming popularity index: http://www.tiobe.com/index.php/content/paperinfo/tpci/index.htmlObjective-C Overview5Strict superset of CC programs are legal Objective-C programsApple's Objective-C support C++Single InheritanceProtocols (java interfaces)Categories (Extending classes)PropertiesSmalltalk messaging syntaxException HandingDynamic runtimeObjects created on heapReflectionBlocksSyntax Additions to C6Anonymous objectClassesSelectorsMessage expressionsProtocol, Category syntaxObjective-C Message Syntax7 Rectangle * sample = [[Rectangle alloc] init]; [sample setWidth:4]; [sample setHeight:5]; [sample setHeight:5 width: 4]; int area = [sample area]; [sample release];Rectangle sample = new Rectangle();sample.setWidth(4);sample.setHeight(5);sample.setHeightWidth(4,5);int area = sample.area();Java Objective-CMessage Syntax8[receiver message][receiver message: argument][receiver message: arg1 and: arg2][receiver message: arg1 and: arg2 with: arg3]Base Date Types9intat least 16 bitsshort intsmaller than int; at least 16 bitslong intat least 32 bitslong long intat least 64 bitsunsigned intat least 16 bitsfloatat least 6 digits of precisiondoubleat least 10 digits of precisionlong doubleat least 10 digits of precisioncharSingle characterunsigned charsigned charBOOL0, 1, TRUE, FALSE, YES, NOfloat _ComplexComplex numberdouble _ComplexExtended accuracy complex numberlong double _ComplexExtra-extended accuracy complex numbervoidBOOL10 BOOL isHome = YES; isHome = NO; isHome = FALSE; isHome = 0; isHome = TRUE; isHome = 1; if (isHome) NSLog(@"home"); else { NSLog(@"away"); }How to Run Programs11Choose Command Line tool to write straight Objective-C code. When we start iPhone applications we will use a different template for projects.Xcode Editor12Strings13NSString C StringNSString* greeting = @"Hi mom"; char* greeting = "Hi Dad";Objective-C Classin Foundation frameworkUsed in iPhone developmentObjective-C array of charWhere are the docs for NSString?14Search for NSString in XcodeGoogle for NSStringor go to Apple Dev center and find NSString classRead String Programming GuideCreating Strings15 NSString * start = @"Start"; NSString * all = [start stringByAppendingString:@" and the rest"]; NSLog(all);Formatting Strings16NSString * formatted = [NSString stringWithFormat:@"Name: %@, Age: %f", @"Sam", 12.3];//Name: Sam, Age: 12.300000Some formats17%@Object%d, %isigned int%uunsigned int%ffloat/double%x, %Xhexadecimal int%ooctal int%zusize_t%ppointer%efloat/double (in scientific notation)%gfloat/double (as %f or %e, depending on value)%sC string (bytes)%SC string (unichar)%ccharacter%Cunichar%lldlong longSee "String Format Specifiers" in Apples "String Programming Guide"NSLog uses formatting18float fromString = [@" 123.45 " floatValue];NSLog(@"Result: %f", fromString);Output2010-08-21 16:42:38.129 examples[29557:a0b] Result: 123.449997Reading From File19 NSString *path = @"/Users/whitney/Desktop/names.txt"; NSError *error; NSString *stringFromFileAtPath = [NSString stringWithContentsOfFile: path encoding: NSUTF8StringEncoding error:&error]; if (stringFromFileAtPath == nil) { NSLog(@"Error reading file at %@\n%@", path, [error localizedFailureReason]); } NSLog(@"Contents:%@", stringFromFileAtPath);First: Roger,Last: WhitneyFirst: Sam,Last: Spadenames.txtScanning a String20 NSScanner *theScanner; NSString *firstName; NSString *lastName; theScanner = [NSScanner scannerWithString: stringFromFileAtPath]; while ([theScanner isAtEnd] == NO) { if ([theScanner scanString: @"First:" intoString: NULL] && [theScanner scanUpToString: @"," intoString: &firstName] && [theScanner scanString: @"," intoString: NULL] && [theScanner scanString: @"Last:" intoString: NULL] && [theScanner scanUpToString: @"\n" intoString: &lastName] ) { NSLog(@"First: %@: Last: %@", firstName, lastName ); } }First: Roger,Last: WhitneyFirst: Sam,Last: Spadenames.txtstringFromFileAtPath is from last slideDerived Data Types21int single[] = { 0, 1, 2 }int byOrder[] = {[2] = 4, [5] = 1, [0] = 8 }int matrix[3][2] = { {1, 2} , {4, 5}, {6, 7 }}struct point { x; y } corner = { 10, 20 };union overlap { int integer; float floater } example = { 10 }enum Days{Sunday,Monday,Tuesday,Wednesday,Thursday,Friday,Saturday} exam;exam = Monday;Standard C Control Structures22fordowhileifswitchnil23Java's null that responds to messagesRectangle* test = nil;int area = [test area];// runs without errorRulesmessage returns[nil message] returnsobjectnilpointer, int, long, double (numberic types)0struct in registerall values
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