我们知道在mac或iphone上编程最终逃不开os x平台,你无法在windows或linux上开发纯正的apple程序.(so不要舍不得银子买mac啦)虽说linux和windows上有移植的obj-c编译器,但是平台开发框架还是在mac上啊.比如cocoa框架包括Foundation框架,Application Kit框架和Core Data的第三方框架;二cocoa Touch指的则是Foundation,Core Data以及UIKit框架.对于Foundation框架中各个类的使用,可以到apple开发者网站在线查询:https://developer.apple.com/library/mac/navigation/
接下来我们不按顺序,专挑难点,奇怪点和好玩点(如果有的话)的类来看看,直接用代码说话喽
#import<Foundation/Foundation.h>
int main(int argc, char *argv[]){
@autoreleasepool {
NSNumber *n;
NSInteger integer; //not a class just a typedef
n = [NSNumber numberWithInteger: 101];
integer = [n integerValue];
NSLog(@"%li",(long)integer);
NSNumber *n1 = [[NSNumber alloc] initWithLong:0x12345678];
[n1 initWithLong :0xabcd]; //can't change org value 0x12345678!
integer = [n1 longValue];
NSLog(@"%lx",(long)integer);
NSString *str = @"hello apple";
NSLog(@"str is : %@",str);
NSLog(@"num is : %@",n);
NSLog(@"Hello World!");
}
return 0;
}
注意代码中%@打印NSNumber型变量的行了吗?有人可能会问这是怎么实现的,我开始也以为%@只能格式化显示NSString类型啊.其实只要类中定义了description方法,就可以以自定义格式显示任何对象的内容啦.这个我们来写个简单类试一下:
#import<Foundation/Foundation.h>
@interface A:NSObject{
int i;
}
-(id)init:(int)i_v;
@end
@implementation A
-(id)init:(int)i_v{
self = [super init];
if(self){
i = i_v;
}
return self;
}
-(NSString*)description{
return [NSString stringWithFormat:@"#i is %d#",i];
}
@end
int main(int argc, char *argv[]){
@autoreleasepool {
A *a = [[A alloc] init:99];
NSLog(@"a is %@",a);
}
return 0;
}
注意description方法的实现中stringWithFormat方法的2个参数分割符哦,不是:号而是逗号(,)哦.执行结果如下
wisy@wisy-ThinkPad-X61:~/src/objc_src$ clang -O3 -g0 $OBJ_C_OPT -lobjc -lgnustep-base -o f f.m wisy@wisy-ThinkPad-X61:~/src/objc_src$ ./f 2014-07-01 12:42:59.380 f[4179] a is #i is 99#
Foundation中的字符串操作看起就显得那么蛋疼,简单的东西给搞的蛮复杂的,尤其是方法名,貌似还驼峰状,我呵呵了.字符串类分为可变和不可变两种,前者类位NSString,后者类为NSMutableString.顾名思义,不可变字符串不可以修改自身,只能返回一个修改后的新字符串,而可变字符串可以修改自身,包括删除subString,拼接啊,替换啊,皆可,下面上代码:
#import<Foundation/Foundation.h>
int main(int argc, char *argv[]){
@autoreleasepool {
NSString *str_no_m = @"hello world";
NSMutableString *str_m;
NSRange substr; //just a struct
str_m = [NSMutableString stringWithString: str_no_m];
NSLog(@"%@",str_m);
[str_m insertString: @" xxx" atIndex: 5];
NSLog(@"%@",str_m);
[str_m appendString: @" not_fix!"];
NSLog(@"%@",str_m);
[str_m deleteCharactersInRange: NSMakeRange(6,4)]; //(index,len)
NSLog(@"%@",str_m);
substr = NSMakeRange(6,6);
[str_m deleteCharactersInRange: substr];
NSLog(@"%@",str_m);
substr = [str_m rangeOfString: @"_"];
if(substr.location != NSNotFound){
[str_m deleteCharactersInRange: substr];
}
NSLog(@"%@",str_m);
[str_m setString: @"new string!"];
NSLog(@"%@",str_m);
substr = [str_m rangeOfString: @"new"];
if(substr.location != NSNotFound){
[str_m replaceCharactersInRange: substr withString: @"old"];
}
NSLog(@"%@",str_m);
[str_m setString: @"1122334411223344"];
[str_m replaceOccurrencesOfString:@"2" withString:@"X" \
options:0 range:NSMakeRange(0,[str_m length])];
NSLog(@"%@",str_m);
}
return 0;
}
编译及运行结果如下:
wisy@wisy-ThinkPad-X61:~/src/objc_src$ clang -O3 -g0 $OBJ_C_OPT -lobjc -lgnustep-base -o f f.m wisy@wisy-ThinkPad-X61:~/src/objc_src$ ./f 2014-07-01 14:36:49.380 f[5719] hello world 2014-07-01 14:36:49.382 f[5719] hello xxx world 2014-07-01 14:36:49.382 f[5719] hello xxx world not_fix! 2014-07-01 14:36:49.383 f[5719] hello world not_fix! 2014-07-01 14:36:49.383 f[5719] hello not_fix! 2014-07-01 14:36:49.383 f[5719] hello notfix! 2014-07-01 14:36:49.383 f[5719] new string! 2014-07-01 14:36:49.383 f[5719] old string! 2014-07-01 14:36:49.383 f[5719] 11XX334411XX3344
注意其中的replaceOccurrencesOfString方法,其中的options可能的选项有:
Search and Comparison Options
Several of the search and comparison methods take an “options” argument. This is a bit mask that adds further constraints to the operation. You create the mask by combining the following options (not all options are available for every method):
NSLiteralSearch
option were specified.
至于我用的值0,我猜是默认选项吧?因为书上值为nil,编译有警告,遂换为0.