object-c基础知识复习

最新推荐文章于 2023-04-26 18:56:47 发布

翻译最新推荐文章于 2023-04-26 18:56:47 发布 · 1k 阅读

文章标签：

#getter #float #setter #string #c

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本文探讨了Cocoa与Swift在iOS开发领域的应用，深入解析了这两种技术的特点与优势，通过实例展示了如何利用它们进行高效开发。

int main(int argc,const char *argv[])
{
    return 0;
}

0代表程序是正常退出，任何非0的返回值代表有错误产生

NSLog输出各种数据类型的表达式

#import <Foundation/Foundation.h>

int main(int argc, const char * argv[])
{

    @autoreleasepool {
        
        char a       = 'a';
        short int  sint  = 12;
        unsigned short int usint = 22;
        int intVar = 32;
        unsigned int uintVar = 42;
        long int lintVar = 52;
        unsigned long int ulongIntVar= 62;
        long long int llintVar = 500ll;
        unsigned long long int ullintVar = 12ull;
        float floatVar = 12.34f;
        double  doubleVar = 12.34;
        long double ldoubleVar = 12.34L;
        id idVar = nil;
        NSString *name = @"test";
        BOOL isTrue = YES;

        NSLog(@"bool = %i",isTrue);//布尔值
        NSLog(@"String = %@",name);//字符串
        NSLog(@"charVar = %c",a);//字符
        NSLog(@"shortIntVar: hi:%hi,hx:%hx,ho:%ho",sint,sint,sint);//十进制，十六进制，八进制short int
        NSLog(@"unsignedShortIntVar: hu:%hu,hx:%hx,ho:%ho",usint,usint,usint);//十进制，十六进制，八进制unsigned short int
        NSLog(@"intValue:i:%i,x:%x,o:%o",intVar,intVar,intVar);//十进制，十六进制，八进制int
        NSLog(@"unsigned int Value:u:%u,x:%x,o:%o",uintVar,uintVar,uintVar);//十进制，十六进制，八进制unsigned int
        NSLog(@"long int:li:%li,lx:%lx,lo:%lo",lintVar,lintVar,lintVar);//十进制，十六进制，八进制long int
        NSLog(@"unsigned long int:lu:%lu,lx:%lx,lo:%lo",ulongIntVar,ulongIntVar,ulongIntVar);//十进制，十六进制，八进制unsigned long int
        NSLog(@"long long int:lli:%lli,llx:%llx,llo:%llo",llintVar,llintVar,llintVar);//十进制，十六进制，八进制unsigned long long int
        NSLog(@"unsigned long long int:llu:%llu,llx:%llx,llo:%llo",ullintVar,ullintVar,ullintVar);//十进制，十六进制，八进制unsigned long long int
        NSLog(@"float:f:%f,e:%e,g:%g,a:%a",floatVar,floatVar,floatVar,floatVar);//float
        NSLog(@"double:f:%f,e:%e,g:%g,a:%a",doubleVar,doubleVar,doubleVar,doubleVar);//double
        NSLog(@"long double:Lf:%Lf,Le:%Le,Lg:%Lg",ldoubleVar,ldoubleVar,ldoubleVar);//long double
        NSLog(@"id:p=%p",idVar);//id

        
    }
    return 0;
}

键盘输入的示例

#import <Foundation/Foundation.h>

int main(int argc, const char * argv[])
{

    @autoreleasepool {
        
        int n,number,triangularNumber;
        
        NSLog(@"What triangular number do you want?");
        scanf("%i",&number);
        
        triangularNumber = 0;
        for (n  = 1; n<= number; ++n)
        {
            triangularNumber += n;
        }
        
        NSLog(@"Triangular number %i is %i\n",number,triangularNumber);
    }
    return 0;
}

对象用.符号获得属性，相当于调用其的setter和getter方法

instance.property = value 相当于[instance setProperty:value]

动态类型的一些常用函数

-(BOOL) isKindOfClass: class-object 判断该对象是否是class-object或其子类的实例

-(BOOL) isMemberOfClass:class-object 判断该对象是否是class-object的实例

-(BOOL) respondsToSelector:selector 判断该类是否响应selector方法

+(BOOL) instancesRespondToSelector:selector 判断该类的实例是否响应selector方法

+(BOOL)isSubclassOfClass:class-object 该类是否是class-object的子类

-(id) performSelector: selector 调用selector方法

-(id) performSelector:selector withObject:object 调用selector方法，object为该方法的参数

-(id) performSelector:selector withObject:object1 withObject:object2调用selector方法，object1,object2为该方法的两个参数

异常的例子:

#import <Foundation/Foundation.h>

@interface testClass : NSObject
{
}
@end

@implementation testClass
@end

int main(int argc, const char * argv[])
{

    @autoreleasepool{
    
        testClass *tc = [[testClass alloc] init];
        
        @try {
            [tc noSuchMethod];
        }
        @catch (NSException *exception) {
            NSLog(@"Caught %@%@",[exception name],[exception reason]);
        }
        @finally {
        }
        NSLog(@"Execution continues");
        [tc release];
    }
    return 0;
}

block实例

int main(int argc, const char * argv[])
{

    @autoreleasepool{
    
        void (^print_message)(void) =
        ^(void){
            NSLog(@"Programming is fun.");
        };
       
        print_message();
        
        //block可以访问当它定义的时候的区域外的变量
        int foo = 10;
        void (^printFoo)(void) =
            ^(void)
            {
                NSLog(@"foo = %i",foo);//这个值是10，不是15
                //foo = 20;               //这会产生一个编译错误，它不能改变这个变量的值
            };
        
        foo = 15;
        
        printFoo();
    }
    return 0;
}

如果变量foo前面加一个__block,那就可以在block里面改变它的值了

int main(int argc, const char * argv[])
{

    @autoreleasepool{
    
        void (^print_message)(void) =
        ^(void){
            NSLog(@"Programming is fun.");
        };
       
        print_message();
        
        __block int foo = 10;
        void (^printFoo)(void) =
            ^(void)
            {
                NSLog(@"foo = %i",foo);
                foo = 20;              
            };
        
        foo = 15;
        
        printFoo();
        NSLog(@"foo = %i",foo);
    }
    return 0;
}

结果为:
foo = 15
foo = 20

结构体的初始化方法

int main(int argc, const char * argv[])
{

    @autoreleasepool{
        
        struct date
        {
            int month;
            int day;
            int year;
        };
        
        struct date today;
        
        today.month = 9;
        today.day   = 25;
        today.year  = 2011;
        
        NSLog(@"Today's date %i/%i/%.2i.",today.month,today.day,today.year %100);
        
        struct date t1 = {7,2,2011};
        struct date t2 = {7};
        struct date t3 = {.month = 7,.day = 2, .year = 2011};
        struct date t4 = {.year = 2011};
    }
    return 0;
}

在ARC内存管理模式下，一般来说都不必自己写dealloc方法，如果必须重写dealloc方法，也不需要调用父类的dealloc方法，编译器会自己填上去