數(shù)組,字典對象初始化時,一定要判斷添加的元素是否為nil.否則不是崩潰,就是數(shù)據(jù)和預(yù)期不一致.

        NSString *ss = nil;
        
        NSArray *ar = [NSArray arrayWithObjects:@"dsa",ss, @"dsf", nil];
        NSLog(@"%@", ar); //雖然不崩潰,但數(shù)據(jù)和預(yù)期不一致
//        NSString *a = ar[2]; //由預(yù)期數(shù)據(jù)不一致,導(dǎo)致的數(shù)組越界.
//        NSLog(@"%@", a);
        
        /*
         *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[__NSPlaceholderArray initWithObjects:count:]: attempt to insert nil object from objects[1]'
         ***
         */
//        NSArray *sd = @[@"sf", ss, @"fd"]; //使用語法糖,對于數(shù)組,里面的元素不能為nil.
//        NSLog(@"%@", sd);
        
        /*
         *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '+[NSDictionary dictionaryWithObjectsAndKeys:]: second object of each pair must be non-nil.  Or, did you forget to nil-terminate your parameter list?'
         ***
         */
//        NSDictionary *d = [NSDictionary dictionaryWithObjectsAndKeys:@"sd",@"key1",@"sf",ss, @"sds",@"key3", nil];
//        NSLog(@"%@", d);
        
        NSDictionary *d2 = [NSDictionary dictionaryWithObjectsAndKeys:@"sd",@"key1",ss,@"sds", nil];
        NSLog(@"%@", d2); //雖然不崩潰,但數(shù)據(jù)和預(yù)期不一致
        
        /*
         *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[__NSPlaceholderDictionary initWithObjects:forKeys:count:]: attempt to insert nil object from objects[2]'
         ***
         */
        NSDictionary *d3 = @{@"key1":@"sfs", @"key2":@"dsfds", @"key3":ss}; //使用語法糖,對于字典,key和value都不能為nil
        NSLog(@"%@", d3);
       
        NSMutableDictionary *mD = [NSMutableDictionary dictionaryWithCapacity:1];
    NSString *ss = nil;
    mD[@"sf"] = ss; //不會崩潰
    NSLog(@"%@", mD);

        NSMutableDictionary *mD = nil;
        [mD setObject:<#(nonnull id)#> forKey:<#(nonnull id<NSCopying>)#>];
        [mD setValue:<#(nullable id)#> forKey:<#(nonnull NSString *)#>];
        使用setObject:方法,object不能為nil,而使用setValue方法,object可以為nil.

使用語法糖,對于數(shù)組,里面的元素不能為nil.
使用語法糖,對于字典,key和value都不能為nil.