How to append a string to NSMutableString

Question

i'm an absolute newbie with objective-c

with this code

NSMutableString *teststring;
[teststring appendString:@"hey"];
NSLog(teststring);

nothing gets displayed in the console.

Surely i'm doing something wrong here... :-)

score 58 · Answer 1 · edited Feb 07 '12 at 17:22

58

You need to create the string first.

NSMutableString *teststring = [[NSMutableString alloc]init];

[teststring appendString:@"hey"];

NSLog(teststring);

Now, it will print.

edited Feb 07 '12 at 17:22

eric.mitchell

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answered Feb 07 '12 at 17:17

Apurv

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Thanks, this fit well for me. – James T Snell Feb 11 '14 at 16:21
Please update your answer like @sly's to prevent a memory leak. – Volkan Ozyilmaz Dec 14 '18 at 08:32
People used to create their project with ARC. So, compiler adds such instruction and nothing to worry. – Apurv Dec 17 '18 at 10:37

score 28 · Accepted Answer · answered Feb 07 '12 at 17:21

28

Change first line to

NSMutableString *teststring = [NSMutableString string];

answered Feb 07 '12 at 17:21

Shmidt

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score 9 · Answer 3 · answered Feb 07 '12 at 17:18

This line

NSMutableString *teststring;

simply establishes a pointer, but does not create anything. Instead, you need to create a new instance of NSMutableString, for example:

NSMutableString *teststring = [[NSMutableString alloc] init];
[teststring appendString:@"hey"];
NSLog("%@", teststring);

score 5 · Answer 4 · answered Feb 07 '12 at 17:19

Sample:

NSMutableString *buffer = [[NSMutableString alloc] init]; // retain count = 1. Because of the "alloc", you have to call a release later

[buffer appendString:@"abc"];
NSLog(@"1 : %@", buffer);
[buffer appendString:@"def"];
NSLog(@"2 : %@", buffer);

[buffer release]; // retain count = 0 => delete object from memory

score 0 · Answer 5 · edited Jun 20 '16 at 17:41

NSMutableString *tag = [NSMutableString stringWithString: @"hello <td> this is inside td </td> 000999 <><> ..<. ><> 00000 <td>uuuuu</td> vvvvv <td> this is also inside td </td>"];  
    NSRange open = [tag rangeOfString:@"<"]; 
    while(open.location != NSNotFound) 
    {
        NSRange close = [tag rangeOfString:@">"]; 
        NSRange string = NSMakeRange(open.location, close.location-open.location+1);
        [tag replaceCharactersInRange:string withString:@""];               
        open =  [tag rangeOfString:@"<"];
        NSLog(@"%@",tag);
    }

How to append a string to NSMutableString

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