Without #import <Foundation/Foundation.h> statement how I am able to use it in my Iphone App

Question

I a new to Objective C and iphone development. I read somewhere that I need to import the header files of foundation framework in my files where I want to use them. But I saw a sample Iphone project which was using NSString, NSDate, NSArray etc but there was never a statement like #import Foundation.h or #import NSString.h or so.

Answer 1

The import was probably in a prefix header . Prefix headers get added to the top of every file that gets compiled.

Answer 2

look at the supporting files there will be a file yourprojectname-Prefix.pch open that up..

there you will se something like...

//
// Prefix header for all source files of the 'yourProject' target in the 'yourProject' project
//

#import <Availability.h>

#ifndef __IPHONE_3_0
#warning "This project uses features only available in iPhone SDK 3.0 and later."
#endif

#ifdef __OBJC__
    #import <UIKit/UIKit.h>
    #import <Foundation/Foundation.h>
#endif

this is automatically added to your file.

Answer 3

您是否查看过Prefix.pch中“ Supporting files”文件夹中的Prefix.pch文件？