"Original" objective-c study note _01 "2015-09-16 23:30"

Dynamic binding

Dynamic Typing Dynamics Check

Dynamic linking dynamically linked

#import <Foundation/Foundation.h>

int main (int argc, const char *argv[]) {

@autoreleasepool {//auto-free pool

NSLog (@ "Hello world!"); Want the console output string

}

return 0;

}

1 Import header file to prevent duplicate inclusion

Include is to prevent duplicate containment by using pre-processing directives, which cannot be controlled if pre-processing directives are not written

2 The difference between import and @class

3 Foundation and Foundation.h header files. Contains some other header files

Include this header file, equal to the introduction of all OC Library files

4 the difference between NSLog and printf

NSLog can automatically break the log (time + project information) parameter is an object of type NSString

PRINTD cannot wrap a log parameter is a string constant pointer

NSLog formatted output problem:

1 can be formatted output 2 with%@ output string 3 nsstring *str = "ds"; NSLog (@ "%@", str);

The function of the @ symbol:

1 @ Converts a C string into a NSString string object in OC

2 @ identifier OC Most of the keywords start with @

Comments:

1 single-line comment://

2 Multiline Comments:/* */

3 Documentation Notes:/** */

"Original" objective-c study note _01 "2015-09-16 23:30"