NSError && NSException

NSError和NSException的异同：
NSError是非致命的，可恢复的错误。NSError 被捕获的问题是用户错误，通常可以通过错误信息中进行恢复，并且预期或可以预测的错误（如打开没有权限访问的文件）。
NSException是专为潜在的致命的程序错误，这些错误的设计意味着应用程序中存在潜大的缺陷，你没有正确地检查先决条件而执行某些操作（如试图访问数组索引超出其边界，试图改变不可改变的对象）
参考文章：Exception Programming Guide
参考博客：http://stackoverflow.com/questions/11100951/nsexception-and-nserror-custom-exception-error

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NSException的成员属性与方法
成员：
– name 异常名字
– reason 出现异常的理由
– userInfo 包含应用具体异常信息

@property(readonly, copy) NSArray *callStackReturnAddresses 错误回调堆栈地址信息@property(readonly, copy) NSArray *callStackSymbols 

An array of strings describing the call stack backtrace at the moment the exception was first raised. The format of each string is determined by the backtrace_symbols() API

方法：
创建一个异常

+ exceptionWithName:reason:userInfo:

Creates and returns an exception object .

Declarat
+ (NSException *)exceptionWithName:(NSString *)name reason:(NSString *)reason userInfo:(NSDictionary *)userInfoameters
name
The name of the exception.
reason
A human-readable message string summarizing the reason for the exception.
userInfo
A dictionary containing user-defined information relating to the exception

创建并抛出异常
+ raise:format:
A convenience method that creates and raises an exception.

Declaration

OBJECTIVE-C
+ (void)raise:(NSString )name format:(NSString )format,, …
Parameters
name
The name of the exception.

format,
A human-readable message string (that is, the exception reason) with conversion specifications for the variable arguments that follow.

…
Variable information to be inserted into the formatted exception reason (in the manner of printf).

• initWithName:reason:userInfo:
  Designated Initializer
  Initializes and returns a newly allocated exception object.

Declaration

SWIFT
init(name name: String, reason reason: String?, userInfo userInfo: [NSObject : AnyObject]?)

OBJECTIVE-C
- (instancetype)initWithName:(NSString )name reason:(NSString )reason userInfo:(NSDictionary *)userInfo

Parameters
name
The name of the exception.
reason
A human-readable message string summarizing the reason for the exception.
userInfo
A dictionary containing user-defined information relating to the exception
Return Value
The created NSException object or nil if the object couldn’t be created.

PS:

@interface ZhouCHong : NSObject@property (nonatomic, strong) NSString* name;@end@implementation ZhouCHong-(void)dealloc{    NSLog(@"%s",__FUNCTION__);}@endint main(int argc, const char * argv[]) {    @autoreleasepool {        int i=0;        NSArray *array=@[@"1"];        ZhouCHong* zc;        @try {            zc = [[ZhouCHong alloc] init];            zc.name = array[1];//此处会抛出数组越界异常，          //这后面的代码将不在执行            ！！！！此处zc对象将不会释放，存在内存泄漏        }        @catch (NSException *exception) {            NSLog(@"%@",exception);//捕捉到异常，并处理        }        @finally {            i=100;        }        NSLog(@"%d",i);    }    return 0;}