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NSLog method
In order to print logs, we use the NSLog method in Objective-C programming language which we have used right from the Hello World example.
Let us look at a simple code that would print the words “Hello World” −
#import <Foundation/Foundation.h>
int main() {
NSLog(@"Hello, World! n");
return 0;
}
Now, when we compile and run the program, we will get the following result.
2013-09-16 00:32:50.888 demo[16669] Hello, World!
Disabling logs in Live apps
Since the NSLogs we use in our application, it will be printed in logs of device and it is not good to print logs in a live build. Hence, we use a type definition for printing logs and we can use them as shown below.
#import <Foundation/Foundation.h>
#if DEBUG == 0
#define DebugLog(...)
#elif DEBUG == 1
#define DebugLog(...) NSLog(__VA_ARGS__)
#endif
int main() {
DebugLog(@"Debug log, our custom addition gets
printed during debug only" );
NSLog(@"NSLog gets printed always" );
return 0;
}
Now, when we compile and run the program in debug mode, we will get the following result.
2013-09-11 02:47:07.723 demo[618] Debug log, our custom addition gets printed during debug only 2013-09-11 02:47:07.723 demo[618] NSLog gets printed always
Now, when we compile and run the program in release mode, we will get the following result.
2013-09-11 02:47:45.248 demo[3158] NSLog gets printed always
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