Obj-C iOS Calculator

The Homework 1 my first iOS app from NTU101-1 MMP Course

by NTU Michael Hsu

This homework's importance

some variable type

1. NSString是self.display.text
2. NSNumber *Memory;
3. NSString *Operator;
4. double result;

NSNumber to double

[self.Memory doubleValue] 

double to NSString

[NSString stringWithFormat:@"%f", result]

NSString to double

[self.display.text doubleValue]

NNSting to NSNumber

_Memory = [NSNumber numberWithDouble:[self.display.text doubleValue]];    

String to NSString

self.display.text = @"0";

NSLoog

NSLog(@"%f",result); //double
NSLog(@"%@", self.Memory);  //NSNumber

Conclusions and Tips to follow

1. @(…) is “boxed literal” //Object
2. 字串比較，不能用switch，用[self.Operator isEqualToString:@"+"]
3. UIButton use sender.currentTitle

Other Resources

1. Stanford University Developing Apps for iOS on iTunes U