I'm new to iPhone development,I want to assign one class in existing class
This is what declare in C#
public partial class UserRegisteration : System.Web.UI.Page
{
//some methods
public class Mime
{
//some methods
}
}
like the above format in Objective-C how to assign one more class in existing class?
Any ideas? Thanks in advance.
Yes you can.I am using one class in existing class . One is extending UIView and other is extending NSObject.
MultiLayout.h
#interface MultiLayout : UIView
{
// methods and properties
}
#end
#interface SingleControl : NSObject
{
// methods and properties
}
#end
MultiLayout.m
#implementation SingleControl
//methods and variables declaration and property synthesization
#end
#implementation MultiLayout
//methods and variables declaration and property synthesization
#end
For getting the static value of SingleControl in MultiLayout . you have to call class method like:
MultiLayout.h
#interface MultiLayout : UIView
{
// methods and properties
}
#end
#interface SingleControl : NSObject
{
// methods and properties
}
// add class method
+(int)getValue;
#end
MultiLayout.m
#implementation SingleControl
// add static value
static int values = 100;
// implement method
+(int)getValue{
return values;
}
#end
#implementation MultiLayout
// call method to get value
[SingleChoiceControl getValue];
#end
If I understand your question correctly, you would do this in your interface file:
#interface Mime
//properties and method declarations
#end
#interface UserRegistration : System.Web.UI.Page
#property (strong, nonatomic) Mime *mimeInstance;
#end
and then in the implementation file you implement both like so:
#implementation Mime
//implementation
#end
#implementation UserRegistration
//implementation
#end
I have written two classes which contains same method (print). I want to access first class print method using second class object. How i can achieve this?
Code:
#interface classA : NSObject
-(void) print;
#end
#implementation classA
-(void) print
{
NSLog(#"hello");
}
#end
#interface classB : classA
-(void) print;
#end
#implementation classB
-(void) print{
NSLog(#"hey");
}
#end
Now i created second class object like
classB *B = [classB alloc]init];
use delegates to access other classes
#protocol
you can do like this way also
#implementation view1
(void)someMethod
{
......code of method...
}
#implementation view2
(void)fistMethod
{
view1 *abc = [[view1 alloc]init];
[abc someMethod];
[abc release];
}
also check this Objective-C call function on another class?
I have a method which is implemented in its super method. And when I run my program. It works fine. How do I suppress this warning? By the way, both methods are in '.m' file.
The code is like this:
ClassA.m
#interface ClassA()
- (void)method;
#end
ClassA.h
#interface ClassA : ClassB
#end
ClassB.m
#interface ClassB()
#end
#implementation ClassB
- (void)method
{
}
And it works OK when I call method in ClassA
You could always implement the method anyway, and call the super method -
-(void)doMyThing {
[super doMyThing];
// do nothing
}
You've got it completly wrong. Popular construction is to have:
ClassB.h
#interface ClassB
- (void)method;
#end
ClassB.m
#interface ClassB()
#end
#implementation ClassB
- (void)method
{
//do nothing or even assert false
}
#end
ClassA.h
#interface ClassA : ClassB
#end
ClassA.m
#interface ClassA()
#end
#implementation ClassA
- (void)method
{
//do your stuff here
}
#end
And that's called method overriding. But if I correctly understand what you are trying to achieve you should have:
ClassB.h
#interface ClassB
- (void)method;
#end
ClassB.m
#interface ClassB()
#end
#implementation ClassB
- (void)method
{
//do your stuff here
}
#end
ClassA.h
#interface ClassA : ClassB
#end
And there is no need to mess up with ClassA, and you can call
ClassA *o=[[ClassA alloc ] init];
[o method];
Then the method is available in classA thanks to inheritance from ClassB.
Sounds like you've declared the method in the .h file when you shouldn't have? Or perhaps the #end is missing from the .h file.
You aren't giving us much to go on. Can we see your full code from the .h and .m?
Having read your code sample, try the following:
ClassA.h
#interface ClassA : ClassB
//ClassB inherits from Class A, so we define 'method' in Class B
//ClassA knows about 'method' by inheritance from class B,
//so 'method' doesn't need to be defined here.
//doStuff will be the method that calls 'method'
- (void)doStuff;
#end
ClassA.m
#interface ClassA
#end
#implementation ClassA
- (void)doStuff
{
//Call 'Method'
[self method];
}
#end
ClassB.h
#interface ClassB
//Define 'method' which will be inherited by ClassA
- (void)method;
#end
ClassB.m
#interface ClassB
#end
#implementation ClassB
- (void)method
{
//'method' does it's thing
NSLog(#"Method has been Called");
}
#end
I just want to know that how to pass the string value from one class to another..
Actually i have two classes.In first class i fetch string value from the array and i just want to use this string value into my second class.Now i don't know how to pass value between this two classes.Please give me some idea to do that.Should i use some class method to pass the value.But i don't know how to use this class methods.How i create the class methods to set the values from one class and then get the same value from class methods.
Thanks for help
Class1.h:
#interface Class1 : NSObject
{
NSArray *arr;
}
- (NSString *)myString;
#end
Class1.m:
#implementation Class1
- (NSString *)myString
{
return [arr objectAtIndex:0];
}
#end
Class2.h:
#interface Class2 : NSObject
{
}
- (void)methodThatUsesStringFromClass1:(Class1 *)c1;
#end
Class2.m:
#implementation Class2
- (void)methodThatUsesStringFromClass1:(Class1 *)c1
{
NSLog(#"The string from class 1 is %#", [c1 myString]);
}
#end
The simplest way is to define public #property in class where you want to pass your object, for example, for NSString:
// CustomClassA.h
#interface CustomClassA : NSObject
{
}
#property (nonatomic, retain) NSString *publicString;
#end
// CustomClassA.m
#implementation CustomClassA
#synthesize publicString;
#end
In your sender:
//somewhere defined CustomClassA objectA;
[objectA setPublicString:#"newValue"];
But you should understand what means retain, #synthesize and other. Also it is not your current question.
you can use appDelegate.YourStringVaraible =#"store your string";
and then use this YourStringVaraible in any class by using appDelegate.YourStringVaraible
pass the string parameter by overriding the init method.
Class1.m
#implementation Class1
Class2 *class2 = [[Class2 alloc] initWithString:myString];
...
#end
Class2.h
#interface Class2 : NSObject
{
NSString *string2;
}
#end
Class2.m
-(id) initWithString:(NSString*)str {
self = [super init];
if(self) {
string2 = str;
}
return(self);
}
I've seen usage of Objective-C protocols get used in a fashion such as the following:
#protocol MyProtocol <NSObject>
#required
#property (readonly) NSString *title;
#optional
- (void) someMethod;
#end
I've seen this format used instead of writing a concrete superclass that subclasses extend. The question is, if you conform to this protocol, do you need to synthesize the properties yourself? If you're extending a superclass, the answer is obviously no, you do not need to. But how does one deal with properties that a protocol requires to conform to?
To my understanding, you still need to declare the instance variables in the header file of an object that conforms to a protocol that requires these properties. In that case, can we assume that they're just a guiding principle? CLearly the same isn't the case for a required method. The compiler will slap your wrist for excluding a required method that a protocol lists. What's the story behind properties though?
Here's an example that generates a compile error (Note: I've trimmed the code which doesn't reflect upon the problem at hand):
MyProtocol.h
#protocol MyProtocol <NSObject>
#required
#property (nonatomic, retain) id anObject;
#optional
TestProtocolsViewController.h
- (void)iDoCoolStuff;
#end
#import <MyProtocol.h>
#interface TestProtocolsViewController : UIViewController <MyProtocol> {
}
#end
TestProtocolsViewController.m
#import "TestProtocolsViewController.h"
#implementation TestProtocolsViewController
#synthesize anObject; // anObject doesn't exist, even though we conform to MyProtocol.
- (void)dealloc {
[anObject release]; //anObject doesn't exist, even though we conform to MyProtocol.
[super dealloc];
}
#end
The protocol is just telling everyone that knows about your class through the protocol, that the property anObject will be there. Protocols are not real, they have no variables or methods themselves - they only describe a specific set of attributes that is true about your class so that objects holding references to them can use them in specific ways.
That means in your class that conforms to your protocol, you have to do everything to make sure anObject works.
#property and #synthesize are at heart two mechanisms that generate code for you. #property is just saying there will be a getter (and/or setter) method for that property name. These days #property alone is enough to also have methods and a storage variable created for you by the system (you used to have to add #sythesize). But you have to have something to access and store the variable.
Here's an example of mine that works perfectly, the protocol definition first of all:
#class ExampleClass;
#protocol ExampleProtocol
#required
// Properties
#property (nonatomic, retain) ExampleClass *item;
#end
Below is a working example of a class supporting this protocol:
#import <UIKit/UIKit.h>
#import "Protocols.h"
#class ExampleClass;
#interface MyObject : NSObject <ExampleProtocol> {
// Property backing store
ExampleClass *item;
}
#implementation MyObject
// Synthesize properties
#synthesize item;
#end
all you have to do really is to drop a
#synthesize title;
in your implementation and you should be all set. it works the same way as just putting the property in your class interface.
Edit:
You may want to do this more specifically:
#synthesize title = _title;
This will fall in line with how xcode's automatic synthesis creates properties and ivars if you use auto-synthesis, so that way if your class has properties from a protocol and a class, some of your ivars won't have the different format which could impact readability.
Suppose I have MyProtocol that declares a name property, and MyClass that conforms to this protocol
Things worth noted
The identifier property in MyClass declares and generates getter, setter and backing _identifier variable
The name property only declares that MyClass has a getter, setter in the header. It does not generate getter, setter implementation and backing variable.
I can’t redeclare this name property, as it already declared by the protocol. Do this will yell an error
#interface MyClass () // Class extension
#property (nonatomic, strong) NSString *name;
#end
How to use property in protocol
So to use MyClass with that name property, we have to do either
Declare the property again (AppDelegate.h does this way)
#interface MyClass : NSObject <MyProtocol>
#property (nonatomic, strong) NSString *name;
#property (nonatomic, strong) NSString *identifier;
#end
Synthesize ourself
#implementation MyClass
#synthesize name;
#end
Example: 2 classes (Person and Serial) want use service of Viewer... and must conform to ViewerProtocol. viewerTypeOfDescription is a mandatory property subscriber classes must conform.
typedef enum ViewerTypeOfDescription {
ViewerDataType_NSString,
ViewerDataType_NSNumber,
} ViewerTypeOfDescription;
#protocol ViewerProtocol
#property ViewerTypeOfDescription viewerTypeOfDescription;
- (id)initConforming;
- (NSString*)nameOfClass;
- (id)dataRepresentation;
#end
#interface Viewer : NSObject
+ (void) printLargeDescription:(id <ViewerProtocol>)object;
#end
#implementation Viewer
+ (void) printLargeDescription:(id <ViewerProtocol>)object {
NSString *data;
NSString *type;
switch ([object viewerTypeOfDescription]) {
case ViewerDataType_NSString: {
data=[object dataRepresentation];
type=#"String";
break;
}
case ViewerDataType_NSNumber: {
data=[(NSNumber*)[object dataRepresentation] stringValue];
type=#"Number";
break;
}
default: {
data=#"";
type=#"Undefined";
break;
}
}
printf("%s [%s(%s)]\n",[data cStringUsingEncoding:NSUTF8StringEncoding],
[[object nameOfClass] cStringUsingEncoding:NSUTF8StringEncoding],
[type cStringUsingEncoding:NSUTF8StringEncoding]);
}
#end
/* A Class Person */
#interface Person : NSObject <ViewerProtocol>
#property NSString *firstname;
#property NSString *lastname;
#end
#implementation Person
// >>
#synthesize viewerTypeOfDescription;
// <<
#synthesize firstname;
#synthesize lastname;
// >>
- (id)initConforming {
if (self=[super init]) {
viewerTypeOfDescription=ViewerDataType_NSString;
}
return self;
}
- (NSString*)nameOfClass {
return [self className];
}
- (NSString*) dataRepresentation {
if (firstname!=nil && lastname!=nil) {
return [NSString stringWithFormat:#"%# %#", firstname, lastname];
} else if (firstname!=nil) {
return [NSString stringWithFormat:#"%#", firstname];
}
return [NSString stringWithFormat:#"%#", lastname];
}
// <<
#end
/* A Class Serial */
#interface Serial : NSObject <ViewerProtocol>
#property NSInteger amount;
#property NSInteger factor;
#end
#implementation Serial
// >>
#synthesize viewerTypeOfDescription;
// <<
#synthesize amount;
#synthesize factor;
// >>
- (id)initConforming {
if (self=[super init]) {
amount=0; factor=0;
viewerTypeOfDescription=ViewerDataType_NSNumber;
}
return self;
}
- (NSString*)nameOfClass {
return [self className];
}
- (NSNumber*) dataRepresentation {
if (factor==0) {
return [NSNumber numberWithInteger:amount];
} else if (amount==0) {
return [NSNumber numberWithInteger:0];
}
return [NSNumber numberWithInteger:(factor*amount)];
}
// <<
#end
int main(int argc, const char * argv[])
{
#autoreleasepool {
Person *duncan=[[Person alloc]initConforming];
duncan.firstname=#"Duncan";
duncan.lastname=#"Smith";
[Viewer printLargeDescription:duncan];
Serial *x890tyu=[[Serial alloc]initConforming];
x890tyu.amount=1564;
[Viewer printLargeDescription:x890tyu];
NSObject *anobject=[[NSObject alloc]init];
//[Viewer printLargeDescription:anobject];
//<< compilator claim an issue the object does not conform to protocol
}
return 0;
}
An other Example with Protocol inheritance over subClassing
typedef enum {
LogerDataType_null,
LogerDataType_int,
LogerDataType_string,
} LogerDataType;
#protocol LogerProtocol
#property size_t numberOfDataItems;
#property LogerDataType dataType;
#property void** data;
#end
#interface Loger : NSObject
+ (void) print:(id<LogerProtocol>)object;
#end
#implementation Loger
+ (void) print:(id<LogerProtocol>)object {
if ([object numberOfDataItems]==0) return;
void **data=[object data];
for (size_t i=0; i<[object numberOfDataItems]; i++) {
switch ([object dataType]) {
case LogerDataType_int: {
printf("%d\n",(int)data[i]);
break;
}
case LogerDataType_string: {
printf("%s\n",(char*)data[i]);
break;
}
default:
break;
}
}
}
#end
// A Master Class
#interface ArrayOfItems : NSObject <LogerProtocol>
#end
#implementation ArrayOfItems
#synthesize dataType;
#synthesize numberOfDataItems;
#synthesize data;
- (id)init {
if (self=[super init]) {
dataType=LogerDataType_null;
numberOfDataItems=0;
}
return self;
}
#end
// A SubClass
#interface ArrayOfInts : ArrayOfItems
#end
#implementation ArrayOfInts
- (id)init {
if (self=[super init]) {
self.dataType=LogerDataType_int;
}
return self;
}
#end
// An other SubClass
#interface ArrayOfStrings : ArrayOfItems
#end
#implementation ArrayOfStrings
- (id)init {
if (self=[super init]) {
self.dataType=LogerDataType_string;
}
return self;
}
#end
int main(int argc, const char * argv[])
{
#autoreleasepool {
ArrayOfInts *arr=[[ArrayOfInts alloc]init];
arr.data=(void*[]){(int*)14,(int*)25,(int*)74};
arr.numberOfDataItems=3;
[Loger print:arr];
ArrayOfStrings *arrstr=[[ArrayOfStrings alloc]init];
arrstr.data=(void*[]){(char*)"string1",(char*)"string2"};
arrstr.numberOfDataItems=2;
[Loger print:arrstr];
}
return 0;
}
The variable, anObject, needs to be defined in your TestProtocolsViewController class definition, the protocol is just informing you that it should be there.
The compiler errors are telling you the truth - the variable doesn't exist. #properties are just helpers after all.