Xcode中字符的宽度（以像素为单位）

Question

I want to write a character to an iPad screen beginning at any pixel. The problem I'm having is determining the width of the last character so that I can position the next character. This is the code I have.

NSString *mathText = @"#h23#D45 73#";
//const char *mathTextStr = "#F23#D45   73#";
UIFont * font = [UIFont fontWithName:@"Times" size:15];
CGContextSetTextPosition( myContext, 100, 100 );
for (int i = 0; i < mathText.length; i++) {
    len = 1;
    NSString *subString = [mathText substringWithRange:NSMakeRange(i, 1)];
    const char *oneChar = [subString UTF8String];
    //CGContextShowTextAtPoint(myContext, x, y,oneChar , 1);
    CGContextShowText(myContext, oneChar, 1);
    CGSize charWidth = [subString sizeWithFont:font];

    x=x+charWidth.width+3;
     NSLog(@"x coordinate = %f", x);
    CGContextSetTextPosition( myContext, x, y );
    }

The problem is the characters seems to be with CGSize charWidth.

Any help appreciated. Thanks.

Answer 1

create a category for UILabel with this function:

-(CGSize)expectedLabelSize{
    return [self.text sizeWithFont:self.font
                 constrainedToSize:self.frame.size
                     lineBreakMode:self.lineBreakMode];
}

call it like: [myLabel expectedLabelSize];