iOS implicit conversion loses integer precision 'unsigned long' to int

淩亂°似流年 2022-08-07 03:56 28阅读 0赞

1、问题

NSArray \*mArray ;

int len = \[mArray count\];           warning   implicit conversion loses integer precision 'unsigned long' to int

2、解决方法

###  ###

### 方法A： ###

int count = (int)[mArray count];

###     ###

### 方法B： ###

NSUInteger count;

**方法C:**

Int count= [NSNumber numberWithLongLong:cmd.length].intValue;

###     ###

3、原因

The `count` method of `NSArray` returns an `NSUInteger`, and on the 64-bit OS X platform

*  `NSUInteger` is defined as `unsigned long`, and
 *  `unsigned long` is a 64-bit unsigned integer.
 *  `int` is a 32-bit integer.

So `int` is a "smaller" datatype than `NSUInteger`, therefore the compiler warning.

See also [NSUInteger][] in the "Foundation Data Types Reference":

> When building 32-bit applications, NSUInteger is a 32-bit unsigned integer. A 64-bit application treats NSUInteger as a 64-bit unsigned integer.

引用自

[http://stackoverflow.com/questions/16918826/objective-c-implicit-conversion-loses-integer-precision-nsuinteger-aka-unsig][http_stackoverflow.com_questions_16918826_objective-c-implicit-conversion-loses-integer-precision-nsuinteger-aka-unsig]

[NSUInteger]: https://developer.apple.com/library/mac/#documentation/Cocoa/Reference/Foundation/Miscellaneous/Foundation_DataTypes/Reference/reference.html#//apple_ref/doc/uid/20000018-SW71
[http_stackoverflow.com_questions_16918826_objective-c-implicit-conversion-loses-integer-precision-nsuinteger-aka-unsig]: http://stackoverflow.com/questions/16918826/objective-c-implicit-conversion-loses-integer-precision-nsuinteger-aka-unsig