1 void stringCreate() 2 { 3     //Don‘t need to release memory by this way 4     NSString *str1 = @"String Sample"; 5     6     NSString *str2 = [[NSString alloc] init]; 7     str2 = @"String sample 2"; 8     [str2 release]; 9    10     NSString *str3 = [[NSString alloc] initWithString:@"String sample 3"];11     [str3 release];12     //Don‘t need to manage memory by static function13     str3 = [NSString stringWithString:@"A String"];14    15     NSString *str4 = [[NSString alloc] initWithUTF8String:"String sample4"];16     [str4 release];17     //No manual memory management, too18     str4 = [NSString stringWithUTF8String:"String 4"];19    20    21     NSString *str5 = [[NSString alloc] initWithFormat:@"My age is %i and height is %.2f", 19, 1.55];22     NSLog(@"String 5 is %@", str5);23     [str5 release];24 }

 1 void readFromFile() 2 { 3     NSString *path = @"/Users/hellovoidworld/Study/Foundation/NSString/file.txt"; 4     5     //This function cannot read Chinese, is expired 6 //    NSString *str1 = [NSString stringWithContentsOfFile:path]; 7     8     NSError *error; 9    10     NSString *str1 = [NSString stringWithContentsOfFile:path encoding:NSUTF8StringEncoding error:&error];11    12     if (error == nil)13     {14         NSLog(@"Read successfully, is %@", str1);15     }16     else17     {18         NSLog(@"Read fail, error is %@", error);19     }20 }

1 void readFromUrl()2 {3     NSURL *url = [NSURL URLWithString:@"file:///Users/hellovoidworld/Study/Foundation/NSString/file.txt"];4     NSString *str2 = [NSString stringWithContentsOfURL:url encoding:NSUTF8StringEncoding error:nil];5     NSLog(@"Read url successfully, is %@", str2);6 }