苹果官网学习笔记-处理Foundation-NSNumber,NSString

1、首先，先看一下一个简单的数据类型的封装和拆装

int a = 5;
NSNumber *numberObject = [NSNumber numberWithInt:a];
int b = [numberObject intValue];

快速的定义

NSNumber *myIntValue = @32;
NSNumber *myDoubleValue = @3.323;
NSNumber *myBollValue = @YES;
NSNumber *myCharValue = @'V';
NSNumber *myFloatValue = @12.5F;

2、字符串

快速创建

NSString *myString = @"sfetcde";
NSString *anotherString = [NSString stringWithFormat:@"%d,%@",1,@"string"];
NSString *cString = [NSString stringWithCString:"A C String" encoding:NSUTF8StringEncoding];

空字符串

NSString *emptystr = [NSString string];

拼接字符串方法

NSString *welcome = @"Welcome";
NSString *beijing = [welcome stringByAppendingString:@" to Beijing"];

比较大小，可使用isEqualToString:

转换大小写：uppercaseString和lowercaseString

从开头截取字符串到指定位置 substringToIndex:

从指定位置截取字符串到末尾的方法substringFromIndex: