Objective C雖然循環不循環

我有一個while循環應該循環遍歷一個條件，但不能多次遍歷整個過程。Objective C雖然循環不循環

這是我的相關代碼：

NSInteger i = 0; 
    while(i <= building.departments.count) 
    { 
     NSLog(@"Number of building departments: %lu", (unsigned long)building.departments.count); 
     NSLog(@"i : %ld", (long)i); 

     UILabel *dtitleLB = [[UILabel alloc] initWithFrame:CGRectMake(5, y, 310, 20)]; 
     dtitleLB.text = ((DBDepartment*)[building.departments objectAtIndex:i]).Name; 
     dtitleLB.textAlignment = UITextAlignmentLeft; 
     dtitleLB.backgroundColor = [UIColor clearColor]; 
     dtitleLB.textColor = [UIColor lightGrayColor]; 
     dtitleLB.font = [UIFont fontWithName:@"Helvetica" size:(16.0)]; 
     [scrollView addSubview:dtitleLB]; 
     y += 30; 

     UIButton* dphoneNB = [UIButton buttonWithType:UIButtonTypeCustom]; 
     [dphoneNB setContentHorizontalAlignment:UIControlContentHorizontalAlignmentLeft]; 
     [dphoneNB setTitleColor:[UIColor colorWithRed:0.3 green:0.3 blue:0.9 alpha:1.0] forState:UIControlStateNormal]; 
     [dphoneNB addTarget:self action:@selector(numberPress:) forControlEvents:UIControlEventTouchUpInside]; 
     [dphoneNB setTitle:((DBDepartment*)[building.departments objectAtIndex:i]).Phone forState:UIControlStateNormal]; i++; 
     dphoneNB.frame = CGRectMake(5, y, 315, 25); 
     [scrollView addSubview:dphoneNB]; 
     y += 30; 

     UIButton* dwebsiteNB = [UIButton buttonWithType:UIButtonTypeCustom]; 
     [dwebsiteNB setContentHorizontalAlignment:UIControlContentHorizontalAlignmentLeft]; 
     [dwebsiteNB setTitleColor:[UIColor colorWithRed:0.3 green:0.3 blue:0.9 alpha:1.0] forState:UIControlStateNormal]; 
     [dwebsiteNB addTarget:self action:@selector(linkPress:) forControlEvents:UIControlEventTouchUpInside]; 
     [dwebsiteNB setTitle:((DBDepartment*)[self->building.departments objectAtIndex:i - 1]).Website forState:UIControlStateNormal]; i++; 
     dwebsiteNB.frame = CGRectMake(5, y, 315, 25); 
     [scrollView addSubview:dwebsiteNB]; 
     y += 30; 

     i++; 
    }

用於第一的NSLog = 1或更大的取決於用戶的選擇（從未0）輸出。第二個NSLog = 0的輸出永遠不會變大。

如果你可以檢查我的代碼，看看是否有任何明顯的錯誤，那將不勝感激。

謝謝！

來源

2013-07-08 VonKoob

「building.departments.count」是否等於0或1？你似乎也在幾個地方增加了「我」。 –

aso在頂部的2個NSLog的輸出會很好 – John

你有多少個部門？ –

不循環（或循環不規律）的原因是因爲您在多個點中增加了i。看下面的幾行（打破了看起來更容易）。

... 
     [dphoneNB setTitle:((DBDepartment*)[building.departments 
     objectAtIndex:i]).Phone forState:UIControlStateNormal]; i++; 
... 
     [dwebsiteNB setTitle:((DBDepartment*)[self->building.departments 
     objectAtIndex:i - 1]).Website forState:UIControlStateNormal]; i++; 
... 
     i++;

作爲替代while環這樣的，一個for循環就足夠了。

來源

2013-07-08 22:01:07

非常感謝你在那裏發現我的錯誤，你完全發現了錯誤！ – VonKoob

有時候，第二組眼睛使所有的區別:) –

@VonKoob原始代碼也非常低效。爲什麼一遍又一遍地提取'Department'對象？在循環的頂部獲取一次，並將其存儲在一個變量中。更好的是，使用'for（DBDepartment * dept in building.departments）'而不是'while'循環。 – rmaddy

Objective C雖然循環不循環

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