iOS學習日記（十）代碼練習

1set，get使用
創建BNRStockHolding類
頭文件聲明如下

#import <Foundation/Foundation.h>
@interface BNRStockHolding : NSObject
{
    CGFloat _purchaseSharePrice;
    CGFloat _currentSharePrice;
    NSInteger _numberOfShares;
}
- (void)setPurchaseSharePrice:(CGFloat)purchaseSharePrice;
- (void)setCurrentSharePrice:(CGFloat)currentSharePrice;
- (void)setNumberOfShares:(NSInteger)numberOfShares;
- (CGFloat)purchaseSharePrice;
- (CGFloat)currentSharePrice;
- (NSInteger)numberOfShares;
- (CGFloat)costInDollars;
- (CGFloat)valueInDollars;
- (void)setMessage:(CGFloat)p current:(CGFloat)c number:(NSInteger)n;
- (void)showMessage;
 

@end

實現如下：

#import "BNRStockHolding.h"

@implementation BNRStockHolding
- (void)setPurchaseSharePrice:(CGFloat)purchaseSharePrice{
    _purchaseSharePrice=purchaseSharePrice;
}
- (void)setCurrentSharePrice:(CGFloat)currentSharePrice{
    _currentSharePrice=currentSharePrice;
}
- (void)setNumberOfShares:(NSInteger)numberOfShares{
    _numberOfShares=numberOfShares;
}

- (CGFloat)purchaseSharePrice{
    return _purchaseSharePrice;
}
- (CGFloat)currentSharePrice{
    return _currentSharePrice;
}
- (NSInteger)numberOfShares{
    return _numberOfShares;
}
- (CGFloat)costInDollars
{
    return _purchaseSharePrice*_numberOfShares;
}
- (CGFloat)valueInDollars
{
    return _currentSharePrice*_numberOfShares;
}

- (void)setMessage:(CGFloat)p current:(CGFloat)c number:(NSInteger)n{
    [self setPurchaseSharePrice:p];
    [self setCurrentSharePrice:c];
    [self setNumberOfShares:n];
}

- (void)showMessage{
    NSLog(@"purchasePrice is %lf",[self purchaseSharePrice]);
    NSLog(@"currentPrice is %lf",[self currentSharePrice]);
    NSLog(@"numberOfShares is %ld",[self numberOfShares]);
    NSLog(@"costInDollars is %lf",[self costInDollars]);
    NSLog(@"valueInDollars is %lf",[self valueInDollars]);
}
@end

主函數測試如下：

#import <Foundation/Foundation.h>
#import"BNRStockHolding.h"

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        BNRStockHolding *s1=[[BNRStockHolding alloc] init];
        BNRStockHolding *s2=[[BNRStockHolding alloc] init];
        BNRStockHolding *s3=[[BNRStockHolding alloc] init];
        [s1 setMessage:2.30 current:4.50 number:40];
        [s2 setMessage:12.19 current:10.56 number:90];
        [s3 setMessage:45.10 current:49.51 number:210];
        
        NSMutableArray *data=[NSMutableArray array];
        [data addObject:s1];
        [data addObject:s2];
        [data addObject:s3];
        for(BNRStockHolding *s in data)
        {
            [s showMessage];
        }
        
    }
    return 0;
}

2屬性的使用
創建一個BNRPerson類
頭文件聲明如下

bmi實現如下

主函數測試操作如下，用set、get方法也可，用點方法也可。

3可變數組練習
main.m文件

4類的繼承練習
創建BNRPerson類
頭文件如下

實現如下：

派生類BNREmployee 繼承BNRPerson
.h文件聲明如下：

實現如下：

對父類的BMI方法進行了重寫
main.m測試如下

5description和dealloc練習

用%@輸出對象信息時，處理%@時程序會先向對象發送description消息，默認以字符串形式返回內存地址。
類的實例被釋放時將執行dealloc方法。
通過重寫dealloc方法和description方法可以監測

定義一個BNRAsset類
頭文件，實現，測試main.m如下



系統調用dealloc方法，輸出了deallocating +重寫的description方法返回的字符串信息。這樣我們就知道了什麼時間 哪個實例被釋放了。