12-3 NSString

#import <Foundation/Foundation.h>
//  NSString
int main(int argc, const char * argv[]) {
    @autoreleasepool {
        NSString *s = @"abcd";
        NSNumber *n = @123;
        NSLog(@"%s", [s UTF8String]);//转化成C语言字符串
        NSLog(@"%@", s);//直接打印oc字符串
        NSLog(@"%@", n);
        
        NSString *formatS = [NSString stringWithFormat:@"hello %s, N:%d", "world", 456];//直接使用stringWithFormat来拼接字符串
        NSLog(@"formatS = %@", formatS);
        
    }
    return 0;
}

NSString.png