NSMutableArray一直覆盖自己，并且只返回一个条目。

Question

我正在编写的for循环一直覆盖自己，我需要能够返回所有的值。如何防止for循环覆盖其自身？

sourceArray = [[NSMutableArray alloc] init];

for (NSString *file in sourceFiles) {


    NSString *sourceFile = [sourcePath stringByAppendingPathComponent:file];
    NSImage *image = [[NSImage alloc] initWithContentsOfFile:sourceFile];
    NSImageRep *rep = [[image representations] objectAtIndex:0];

    sourceArray = [NSMutableArray arrayWithObjects:[NSMutableDictionary dictionaryWithObjectsAndKeys:
                                                        sourceFile.lastPathComponent, @"fileName",
                                                        [NSNumber numberWithLong:rep.pixelsWide], @"width",
                                                        [NSNumber numberWithLong:rep.pixelsHigh], @"height",
                                                        nil], nil];

}

Answer 1

问题是在每次遍历循环时，[NSMutableArray arrayWithObjects:都会替换数组。而是..。

// prettier using modern clang literals...
NSDictionary *d = @{ @"fileName": sourceFile.lastPathComponent, 
                     @"width":    @(rep.pixelsWide),
                     @"height":   @(rep.pixelsHeight) };

// just add to the array we allocated outside the loop
[sourceArray addObject:[d mutableCopy]];