synthesize

Lets say I have a simple class like the following: @interface A { // @public int var; } // @property(some_property) int var; @end When I want to access the variable var, I have some options. If I make var public, I can do this: A objectA = [ [ A alloc ] init ]; NSLog( @"%d", objectA->var ); objectA->var = someNumber; If I make it a property instead, I'll have to do something more like this: A objectA = [ [ A alloc ] init ]; NSLog( @"%d", objectA.var ); // dot-syntax NSLog( @"%d", [ objectA var ] ); // get-syntax [ objectA setVar: someNumber ]; I've tried both and they work fine but my question

If I understand correctly, in Objective-C, properties are automatically synthesized with getters and setters, with the instance variable declared as the property name with an underscore prepended ( _ivar ). So, this code: main.m #import <Foundation/Foundation.h> #import "hello.h" int main(int argc, char *argv[]) { @autoreleasepool { Hello *hello = [[Hello alloc] init]; NSLog(@"%@", hello.myString); return 0; } } hello.h #import <Foundation/Foundation.h> @interface Hello : NSObject @property (copy, nonatomic) NSString *myString; @end hello.m #import "hello.h" @implementation Hello -(Hello *

I have a class with the following header: #import <Foundation/Foundation.h> @interface CustomClass : NSObject @property (strong, nonatomic) NSString *foo; @end With the following implementation that does not show any errors: #import "CustomClass.h" @implementation CustomClass - (void) setFoo:(NSString *)foo { _foo = foo; } @end Being a complete beginner to Objective-C, I am baffled when I add the following method to the implementation: - (NSString *)foo { return _foo; } because now there is an error in the method use of undeclared identifier 'title' and it recommends that I change _foo to foo

So the auto synthesize of properties is awesome. However, when you provide both a getter and a setter, you get an error. @property (strong, nonatomic) NSArray *testArray; - (NSArray *)testArray { return _testArray; } - (void)setTestArray:(NSArray *)testArray { _testArray = testArray; } Error: Use of undeclared identifier '_testArray' . Adding @synthesize testArray = _testArray; solves the problem. I am just wondering why this is? When you provide both getter and setter, there is often just no need for an instance variable at all, i.e. when you just forward those messages or store data in other

Under what conditions is @synthesize automatic in Objective-c? Perhaps when using LLVM 3.0 and up? From reading around the net it seems like @synthesize is unnecessary starting with Xcode 4. However I'm using Xcode 4 and receiving warnings when I don't @synthesize a property. Some of the responses to Why don't properties get automatically synthesized seem to imply @synthesize can be omitted at some point under some circumstances. Another (old) reference hinting that @synthesize might be automatic at some point in the future. As of clang 3.2 (circa February 2012), "default synthesis" (or "auto

As far as I know, since XCode 4.4 the @synthesize will auto-generate the property accessors. But just now I have read a sample of code about NSUndoManager , and in the code it noticed that the @synthesize is added explicitly. Like: @interface RootViewController () @property (nonatomic, strong) NSDateFormatter *dateFormatter; @property (nonatomic, strong) NSUndoManager *undoManager; @end @implementation RootViewController //Must explicitly synthesize this @synthesize undoManager; I am feeling puzzled now... When should I add @synthesize explicitly to my code? Gabriele Petronella There's a lot