Question

I just switched my code from Objective-C to Objective-C++. Everything goes swimmingly except for two lines.

NSString * text1=[[NSString stringWithFormat:@"%.2f",ymax] UTF8String];

This line complains that

error: cannot convert 'const char*' to 'NSString*' in initialization

The second error related to the first is from the line:

CGContextShowTextAtPoint(context, 2, 8, text1, strlen(text1));

It complains that

error: cannot convert 'NSString*' to 'const char*' for argument '1' to 'size_t strlen(const char*)'

Is there something I missed in the differences between ObjC and ObjC++?

Answer 1

You want:

const char * text1 = [[NSString stringWithFormat:@"%.2f", ymax] UTF8String];

Not:

NSString *text1 = [[NSString stringWithFormat:@"%.2f", ymax] UTF8String];

(Notice the return value of -UTF8String.)