外企iOS開發的筆試題

一組外企iOS開發的筆試題，您能回答出來嗎？從羣裏收集來的。

（miki西遊@mikixiyou的文檔，原文連接: http://mikixiyou.iteye.com/blog/1546376  轉載請註明出處和做者）

1 why can't NSArray contain NSInteger Instance? with which extra step can you do it?
2.complete this code so that it becomes syntacticallty correct using no more than one additional word and  square branckets NsInteger myNumber=@"10000";

 

這個我會回答是：

NSInteger myInt = [myString intValue];

 

3.What does the following code do? Variable age is defined as NSInteger It compiles fine..but why does it crash? UILabel *mylabel=[UILabel new]; mylabel.text=age?[NSString stringWithFormat:@"%@",age];@"";

這個個人回答是：定義一個UITable對象，根據age的true或者false來給該對象的text屬性賦值。難道是bool轉換成string時致使的crash?
4.Why does the following code crash as soon as the property is set?What is the simple fix? MeasueStripView.h @Interface MeasueLinealView:UIview { NSUIInteger minvalue;
} @property (nonatomic,assign)NSUIInteger minvalue;
MeasueStripView.m #import "MeasueStripView.h" @implementation MeasueStripView @synthsize minvalue #progma mark Passthrough properties -(void) setMinValue:(NSUIInteger)aVal {
self.minvalue:aVal; } Some other file: MeasueStripView *myMS=[MeasueStripView ww]； myMS.minValue=100;//THis Line crashes..
5.You have a UIView and would like to for it to have rounded corners, What's the Fastest way to achive that|
6 How many methods do you know of performing a piece of code in other thread on IOS4.0 and later version.

關於多線程的問題，只能去翻apple的文檔了。

我查到的方法是： 一、detachNewThreadSelector或performSelectorInBackground 二、NSThread 三、NSOperationQueue